A Level Physics Paper 5 Crash Course

Paper 5 Crash Course A2 Revision | Planning Experimental | lg and ln tables | A Level 9702 Physics

Estimated read time: 1:20

    Summary

    This crash course focuses on how to tackle Cambridge A Level 9702 Paper 5, especially Question 1 on experimental design and Question 2 on data analysis. The speaker shows how to read the question carefully, identify independent, dependent, and constant variables, and build a clear table of what to measure, what instruments to use, and what extra details to include. A worked magnetic-field example demonstrates how to measure induced emf against distance, how to clamp and label a circuit diagram properly, and how to linearize an exponential relationship using logarithms so that a gradient can be used to find the constant k. The video then expands to a trolley-and-pulley example to show how to think about measuring speed, keeping variables constant, and using graph transforms, before finishing with paper 2-style advice on uncertainties, logarithms, and best-fit methods.

      Highlights

      • Start by circling the key physical quantities hidden in the wording of the question ✨
      • Use a meter rule for distance, a voltmeter for induced emf, and clamp both the ruler and the coils securely 🧰
      • If the coil is thick, measure its thickness and correct to the center using half the thickness 📏
      • To keep the magnetic setup fair, fix the AC current and number of turns in the primary coil ⚡
      • Log-transform the relationship so that ln(v) against x becomes a straight line with gradient -k 📉
      • Draw diagrams that are workable, not pretty: support everything, label everything, and leave space to add details 🖊️
      • For trolley experiments, measure speed using distance and time, then use kinematics if direct velocity isn’t available 🚗
      • Paper 2 uncertainty questions often boil down to half-range, gradient differences, or percentage uncertainty rules 🧮

      Key Takeaways

      • Read the question first and let the equation tell you the variables you need to measure 🧠
      • Always separate independent, dependent, and constant variables in a simple table 📋
      • For circuit experiments, label the coils, meters, and power supply clearly and clamp anything that cannot float 🔧
      • If the graph is not straight, linearize the equation until it matches y = mx + c 📈
      • For exponential relationships, use logarithms and remember that the gradient gives the constant you want 🔍
      • Keep experimental conditions fixed with tools like an ammeter, variable resistor, plumb line, or spirit level ⚙️
      • In data analysis, know when to use half-range uncertainty, best-fit/worst-fit lines, and log identities ✍️

      Overview

      The core message of the video is that Paper 5 becomes much easier once you stop trying to memorize fixed templates and instead learn a repeatable method. First, identify the variables from the equation and question statement. Then write down how each variable will be measured, what apparatus is needed, and what extra controls are required to make the experiment valid. That simple structure helps you avoid forgetting marks in the exam.

        The first worked example uses induced emf from two coils separated by a distance. The speaker explains how to design the setup, why alternating current is needed, how to clamp and align the apparatus, and how to measure the coil separation correctly. Since the relationship is exponential, the video shows how to take logarithms, rearrange into straight-line form, and use the gradient to find k.

          The second part switches to a trolley-and-pulley style experiment and then broadens into Paper 2 advice on graphs and uncertainties. The important revision point is that physics data questions usually reward the same habits: choose the right graph, linearize if needed, keep constants fixed, and use the correct uncertainty method. Practice different question styles so you can spot the pattern fast in the exam.

            Chapters

            • 00:00 - 25:00: Paper 5 Overview and Experimental Design Strategy The speaker frames Paper 5 as a two-question exam, emphasizing that Question 1 is usually the hardest because it requires experimental design. They recommend reading the question carefully to extract clues, identify variables from the equation, and organize answers in a table listing the physical quantity, how it will be measured, and any extra details needed for full marks.
            • 25:00 - 50:00: Choosing Variables, Instruments, and Control Conditions Explain how to design the experiment by identifying the independent and dependent variables, then choose an appropriate setup, label the necessary components on the diagram, and state how to measure the key distance or separation using a ruler or meter rule. Include the idea that the graph should be a straight-line plot and that the gradient can be used to obtain the required constant.
            • 50:00 - 75:00: Linearizing Graphs and Extracting Gradients/Intercepts The segment begins by explaining how to linearize a fraction-based physics equation by isolating one variable and rewriting it in straight-line form. The speaker shows that the equation can be rearranged so gradient and y-intercept are identified as specific expressions, then notes that the graph to plot is 1/v² against m, with validity indicated by a straight line with a non-zero y-intercept. The discussion emphasizes that the algebra is just preparation for the mark scheme, and that both the gradient and intercept expressions can be simplified further if needed.
            • 75:00 - 100:00: Worked Experimental Planning Example: Trolley Investigation The speaker reviews several experimental planning and data-processing essentials: which instruments or methods to use for uncommon quantities (e.g., Hall probe for magnetic flux density, newton meter for force, manometer for pressure, wavelength setups like Young double slit/diffraction grating) and emphasizes including the relevant equation and checking past papers/set A and set B examples.
            • 100:00 - 105:00: Question 2: Uncertainties, Logs, and Percentage Error Methods Explains how to calculate absolute uncertainty from repeated measurements by taking half the range between the maximum and minimum values, then applies this to a timing example involving 10 oscillations. The speaker shows how to find the average time, determine the uncertainty from the difference between the largest and smallest readings, and then divide by 10 to convert the uncertainty to the period for one oscillation.

            Paper 5 Crash Course A2 Revision | Planning Experimental | lg and ln tables | A Level 9702 Physics Transcription

            • Segment 1: 00:00 - 02:30 in this in today's discussion in today's discussion we are going to look at uh paper five and it's going to be a speed run crash costing so paper five you i think as you all know will consist of two questions and generally uh most of the struggle is in question one so we'll focus on that first where you have to deal with experimental design so when it comes to experimental design normally i'll tell students try to read the questions because the question will give you all the hints and clues about the things that you need to include in your and in your experiment so i think today we will choose a recent one just to discuss as a example to discuss but i i would choose something that people will generally struggle with which has a circuit drawing because oftentimes uh when there's a circuit that we need to include then that is where the confusion happens so it's been a while since circuit was i mean the circuit base question 5 was asked so i think i will probably choose something from magnetic fields chapter which is a cia's favorite they like themselves a good magnetic field and also it has an equation that students generally don't like which is a bunch of lock and lawns and exponents so if you struggle with exponents um the very basic thing that you need to know is the how to linearize the equation okay let's start so when it comes to experimental design normally you will encounter a scenario that you may or may not see before okay what you got to do is you got to identify all the variables or the physical
            • Segment 2: 00:00 - 02:30 quantities one of the quickest way to do so is to look at the equation okay so normally i'll tell a student as you read all you build a table so the suggested table format in the notes that i've given you okay so you see i say redeemer analyze the situation
            • Segment 3: 02:30 - 05:00 presented pay attention to the equation tabulate the variable and constant so that you don't miss out important points because sometimes if we don't know that we have to write about it it's not that you don't know the thing you just don't know you have to write about the thing okay so normally i would suggest a table that look like this okay so what you have is uh some physical quantity your list download okay and then uh the measurements so always think about what do i use to measure the thing okay and then also what are the extra details that you need to write normally here would be all the marks already except the analysis mark okay so let's look at this question it says that you can very easily tell that we are going to have to measure x-rays or we read the question first law okay so a flat circular coil p is carrying a current produces carrying a current produces a magnetic field when the second coil q is placed with the center of a distance x from coil p and emf is induced okay so we could induce an emf in coil q it is suggested that the v is related to x by this relationship v is v naught e negative kx where v naught and k are constants so i'm going to now circle all the things so we definitely are going to measure the induced emf okay because you want to test the relationship between v and x so that means uh one of it is the dependent one of it is the independent which one is easier for us to control what do you think do you think it's easier to control the distance between
            • Segment 4: 02:30 - 05:00 the coil or the emf induced in the coil then you're thinking of course like it's easier for me to control the distance yeah so this means if let's say you think about the physical quantity so let's say i i draw my table okay so the physical quantity here the independent variable is b i mean x so basically we change x and then the dependent
            • Segment 5: 05:00 - 07:30 will be v measure v doesn't mean that you change you don't have to measure okay if not how do you know how much you change so now once you already identify these two main characters then it's time to think about how do you measure them okay so how you're going to measure your distance x so we're probably going to use something like a meter rule because this is a like a length base variable okay and this meter rule cannot float right maybe you think of like nah i put the meter rule behind here to measure yellow but then the meter rule it cannot float cannot be floating so in this case what we will do is we will probably need to clamp the meter rule and i'm thinking right because this is the center of the coil i also need to account for the fact that you know the coil is thick right so i probably need to measure this this thickness of the coil and then uh take n minus or something like okay so then uh the extra detail additional detail or basically the etc etc here would be to maybe measure the thickness measure the coil thickness okay and then divide by two so whatever this t is to find x i would i would have to add that t over two so what i could do is i could measure the distance from here to here the h to the h of the coil maybe this is a okay whatever alphabet you want to give it uh okay so then you will measure the thickness and then t over two here because you want to measure to the center okay and then t over 2 here as well so you have to write this down so measure thickness and then probably
            • Segment 6: 05:00 - 07:30 using a vernier caliper and then after that talk about t over two okay so all these we will talk about or we will write it out inside your experiment okay later i'll show you the mark scheme okay what about v v here is your induced emf so to measure induced emf we would think about using a
            • Segment 7: 07:30 - 10:00 voltmeter so that means i need a circuit drawing here so i probably need to make a mental note okay now i need to draw a circuit for this particular question are there any additional detail for induced emf right if you want induce emf in q then we need current in p but not just any current the current in p must be alternating because you need the flux inside here to keep changing first in this direction then in this direction so the flux keep flip-flopping flip-flopping like a certain mco policies keep flip-flopping flip-flopping so because that change to cause a change in flux okay you don't need to talk about the theory but you have to know that we will use alternating current in the coil all right so what else so we have v we have x and then design the laboratory experiment to test the resistance between v and x done so you want to test the relationship between these two things explain how your results can be used to determine a value of k so we kind of need to find k and to find k right if let's say i extend my table a bit i also need to consider what should be my constant variable so sometimes it is very obvious what your constant variable is you can tell from the equation go ahead and watch the discussion video for fact match 21. the one goal or constant you can harvest from the equation unfortunately in this equation there's no other constant already because they
            • Segment 8: 07:30 - 10:00 want you to find k and v naught is not really something that you can keep constant so things that you can keep constant right is the ac the alternating current in coil p the number of turns in the coil so they expect you to at least have some basic understanding of the physics that is going on so that you know that if let's say you want to measure the induced emf and coil q whatever that is happening to coil p must be fixed so flux will be nba sine theta
            • Segment 9: 10:00 - 12:30 so right now this one will have to be kept this way all right and then i think that's that's about it of course how do you make sure this one is constant then you must measure using an ammeter all right the alternating current so sometimes uh if let's say you are doing a question with a lot of variables for example i'm going to do this exercise again but for winter 20 okay so this is an example of how you can list things down and then okay hang on one more thing that i miss out okay so you can continue the table but it's actually not really necessary i'm going to find the physical quantity k so a lot of times right the mistakes that students do is that right now you have this so you think about this all we are changing x and then we measure v so maybe in your table so all this is happening in your brain okay so we have different different values of x and then we have different different values of b if i plot a graph of x b against x you look at the equation if i plot v against x i'm not going to get a straight line whatsoever i'll probably go i'm probably going to get something like when x increase v decrease something like this okay so we need a straight line graph to find our k values so in order to make this graph straight line i'll copy the equation first what we do is we will learn both sides so long b is equal to lon b naught e negative kx so when you learn both sides
            • Segment 10: 10:00 - 12:30 this will be lon a plus lon b e negative kx and what will happen is now you can rearrange again and this lon e is one so what you have is negative kx times one because uh we can bring down the exponent so there are a few identities here that i use now i use lon a plus lon b is equal to lon a b so this is a this is b lon a b is long a plus lon b second identity i use is lon a
            • Segment 11: 12:30 - 15:00 to the power of n is equal to n lon a okay can bring down the exponents so this negative kx can shoot down here all right and finally the last one that i use is lon e is one compress your calculator so from here when i rearrange i can have lon v is equal to negative kx plus lon v naught so this looks like the form of y is equal to m x plus c so from here you can see that you want to plot lon v on the y axis and the distance between the coil x on the x axis and after that your gradient is equal to negative k but did they ask you to find gradient or they ask you to find k they ask you to find k-1 so k because you see uh if you look at the statement here it says explain how your result is used to determine the value of k so you must go one step more for your answer you must find k in terms of gradient so k is negative gradient and of course if you want to find b naught your y intercept is equal to lon v naught so v naught is equal to e to the power of y intercept but it's not that they want you to find v naught so you don't write this also never mind so you must also include this inside your right up okay so here's a sample answer that i will allow you to look at and once you draft this out it's a method of putting it together in the form of 15 marks so sometimes students is like miss two pages enough man i run our place so i managed to find a sample script of someone and i'm not going to tell you who who is actually able to
            • Segment 12: 12:30 - 15:00 write this all in one page now but for me i should take more pages okay so let's check out someone else's
            • Segment 13: 15:00 - 17:30 right up here okay so here is some sample solutions for that question okay so the first thing right when you draw something depends on your thought process some people they prefer to draw first because drawing helps them think and then it's easier for them to write some people prefer to write first than draw up to you okay so in this case right if they give you a drawing you're going to start from this one of course you can you could you could say why don't i draw in a 3d format because i don't want to if i draw a 3d format the diagram is just harder to draw and here are some examples of diagrams that are quite okay all right this one is okay 3d this one is also this one is weird okay so the first issue right is that whatever that cannot stand okay must be clamped you cannot have things floating around so your coil have to clamp your coil has to clamp so make sure you clamp the coils here to here you clamp the coils here to here the second thing that you should know is that the ruler have to be clamped so you can see i clamped the ruler i climbed the coil i climbed the ruler i'm happy now but i also need to make sure the ruler is parallel to the ground right that's why there's a spirit level here okay and i also need to make sure the coil is not tilted so there's plumb line here so if we go back to the list of you know go back to these nodes you will see that i provided suggestion about set up here okay so whenever you measure meter rule you must clamp and then use plumb line or set square
            • Segment 14: 15:00 - 17:30 and then you clearly draw out the distance okay so it doesn't matter whether it's vertical or horizontal basically any kind of length okay or let's say you want to measure length of certain things okay so if there is no movement the point here is to clamp down everything and then use a spirit level or a plumb line to make sure everything is aligned properly like this one is 90 degree and this one is this one is parallel to this one so you check this plumb line this is the plumb line all right this is the plumb line you're making sure that they are aligned okay so once you clip everything already second thing i mentioned just now is that you must have a
            • Segment 15: 17:30 - 20:00 way to measure the induced emf so on your diagram a general rule of thumb is you must draw the main instrument for example the main instrument for this experiment would be the coil [Music] and then after that you have to support things that you cannot put on the table if you put a coil on the table the coil cannot be vertical so support if needed and then after that draw the measuring instrument for all the variables that you listed down in your in your notes so if you look at this one probably you need to draw meter rule and clamp probably you need to draw voltmeter because we need to know where to put these measuring instruments in the diagram so here the measuring instrument is a ruler so make sure you draw it and then second one is the voltmeter so we want to find the okay so this there's a small error here didn't label coil p and coil q so coil q should be connected to a voltmeter because we want to measure the induced emf in coil q and coil p is the one that is connected to an alternating current so the power supply symbol for alternating current is the waveform symbol like this the form of a wave okay so if you put alternating current inside here then you will create a changing magnetic field and then it will induce the emf here we need an ammeter and we need a real stack because remember this current is kept constant so sometimes you may write halfway and then it's not a neat thing one it's not like you have this you dream about this
            • Segment 16: 17:30 - 20:00 and you can draw the whole thing so for certain people they will start writing and then they notice that hey i miss out this part and then they will have to add to it so generally speaking you could draw something that is very big like this generally i would suggest student that you are a little bit smaller so you have space to add to the site especially if you're not sure so the first thing or the first uh format that i want to mention is that you will always start with defining the problem so please use point form normally students when they don't use point form also weird things can happen so you define the problem p2 so i prefer something like this the independent variable is the distance x between the center of the coil or you could say change x dependent variable is the induced emf in coil q and we call this e
            • Segment 17: 20:00 - 22:30 this one should be v okay because the equation use veeam constant variable is the current in coil p number of turns of coils and the frequency of alternating current so this one requires again a bit more understanding about induced emf because uh if the frequency is high it means that the the current changes more quickly so there's a larger induced emf so basically got to keep the ac constant now all right so sometimes you're wondering what if i don't mention frequency of ac if you don't mention frequency of ac you won't get this d3 mark but this d3 is additional detail so in paper 5 question 1 you can score more than 15 marks so any kind of this d marks you don't write you there's still a chance for you to get 15 out of 15 provided you write all the other p max so you state the problem something like this then the next one we go to method you can write a header if you want okay so your student didn't bother write a header also so here you can see it says use a large number of turns or high frequency current for larger induced emf yeah definitely because this induced ems is very small and then generally these coils will become very hot hang on hot coil can write as safety can okay so don't touch coils or use heat glove as a cause maybe hot so you see i can see the thought process of this human being okay so now we already decide what current to set up here okay then we need to figure out how to you know measure x so use a vernier caliper to find the width of the coil then divide by 2 to find the center of the coil and then
            • Segment 18: 20:00 - 22:30 measure x okay so something like that measure x at different places along the coil to find average so whenever you measure a circular shape right if you again go back to the nodes i've given to you any kind of like diameter or thickness use a vernier caliper or micrometer repeat at different position and average and you can never measure the radius so if they want you to measure a radius for example a cylinder you can't measure the radius of a cylinder what you can measure is a diameter and then you divide by two okay we can't measure the radius of anything with a vernier caliper
            • Segment 19: 22:30 - 25:00 all right anyway after please mention and find average because if you don't write n find average then [Music] game over okay use a variable resistor to ensure that the current is constant so oftentimes right when you think about your constant variable here you also should mention how to keep constant so for current it's very straightforward like we need just use a variable resistor or a real stack okay so make sure the coils are at the same height above the bench with a ruler use a plumb line to measure both to ensure both coils are vertical okay so i prefer if this candidate says and measure x using a ruler but he or she did draw a ruler here see and label so i can give that mark so this is like an insurance law but you want to double ensure yourself can draw the ruler in the position and then say using a meter rule okay so uh make sure the coils are in the same height above the bench or the table with a ruler then use a plumb line to ensure the coils are vertical all right so linearize the equation to this one so whether you want to show all this working or not it's up to you not everybody need that many steps one if you are if you are good in maths or if you are taking a2 max you definitely can hip and scope hip and hop your way to this format very soon so for a levels for paper five physics this final line has one mark this final line here long b is equal to negative kx plus long v naught has one month
            • Segment 20: 22:30 - 25:00 so this student lazy to write or maybe the student right in the question page so just transfer that equation over though so this one okay and then if the relationship is valid so this equation is slightly different because it's not the identical question if the relationship is valid the graph will be a straight line with a y-intercept and negative gradient so you need to measure the y-intercept okay if a graph of lon v against x is plotted k is equal to negative gradient okay and
            • Segment 21: 25:00 - 27:30 then this question actually asks them to find the sec the y-intercept okay so this is a slightly different question but very similar as well so you can see this one when you look at the max scheme right every line is one model so you define the problem i prefer to use the term dependent and independent or you can say vary exchange x measure e okay keep the peak current in the coil constant so this two is one mark each so if you look at the label diagram it should involve coil p and coil two and it has to be supported normally this support is in the form of a stand okay so support that generally is not accepted is uh you know this one where they tie a string and hang there and then you sneeze and then this thing is just gonna what is going on okay uh yeah this one is a okay support but i don't know why they have to draw the circuit out this way but sure okay this is okay this is okay it's very similar to the previous one and they even draw the eye level which is great and they indicated how to measure the distance x and this distance l okay so all this is pretty okay drawing you don't have to draw very nicely you just have to make sure all the things that need to be there are there so this student use set square all over the place okay sure okay let's go back to the mark scheme okay what else do we need we need to mark x and we need to label coil p and q because without p and q and x there's no experiment okay so you have two circuit diagrams one is the ac power supply or the signal
            • Segment 22: 25:00 - 27:30 generator connected to point p and then with the ammeter and then voltmeter and or a cro connected to coil queue so if you just put the ac supply without a real stat it's still okay you will still get this mark because all the rules that are that one all is additional marks later so for a method to determine x okay use a ruler or ruler shown on diagram adjacent to the coil so you should draw where you would want to place the ruler imagine you are writing instruction for a friend who has never done any lab before find your favorite friend who is not a science student you go like bro i need your help read my instruction and see whether you
            • Segment 23: 27:30 - 30:00 understand what is going on and what to measure if the person don't understand means you can refine your working uh that's how people test recipe books they they write a recipe and then they pass to their friend who actually don't really cook and see where their friend can follow the recipe you know think about it that way you're giving instructions to someone who has never done this any of this before okay so m4 your method so basically first you say measure x using a meter rule and you draw the middle rule you get one mark already but the one about the width of the coil is the sentence so the sentence could be measure the width of each coil and divide by two and add to the separation of the coil so what we'll do is we will measure from here to here but for me right i i would write a plus t over two plus t over two because plus or w one over two plus w two over two because i write equation is pretty straightforward okay so matter of analysis you put a graph of lon v against x and k is negative gradient for the correct graph so these are all the extra details that we can we can add okay so for example do not touch the hot coil use glove to position the hot coil use a large current use high frequency keep the number of turns constant or the frequency constant okay how to check the current is constant adjust a variable resistor and keep emitter reading constant measure so whenever you want to repeat measurement for circular object mention that you measure x at different parts the word different has to be there and average then
            • Segment 24: 27:30 - 30:00 uh position ruler horizontally so use a spirit level or measure same height from the bench on both ends so you measure h1 here you measure h2 here they make sure they are the same provided your bench or your table top is okay all right and then you also must have a way to keep the coils parallel uh until maximum use a set square to ensure the coils are right angle plumb line would work too okay the equation and the relationship is valid if it's a straight line produced okay so this is generally how it would look like okay uh this equation doesn't look like this equation because it's a slightly
            • Segment 25: 30:00 - 32:30 different question okay but the format almost any every one of it is the same what means that means they repeat almost entirely yes for this one yes but they don't always repeat that so don't don't hope for that or rather you also don't know which one they will repeat right so just study everything wrong so if you look at all of this we have so many different experiments that you need to think about okay so normally uh what i would suggest is that you go through the past years and then just think about how you would write it and then if let's say you don't know how to draw the diagram then discuss with your teacher or come and talk to me okay so when it comes to the format right if you want to follow this format it kind of settles off most of the things because here i go talk about things like normally it will be okay so for diagram it can be two to three marks in the diagram depending on the max game area is different so if you got diagram to copy you copy sometimes they don't give diagram which is a sadness okay and then all items needed to measure the variables are clearly labeled and positioned at the right place draw a circuit diagram if you are doing a circuit experiment like for example to the first example we did today was a circuit one clamp and secure all objects that need support unless you're talking about like uh placing uh uh most things this a little bit of support one so uh if it cannot float you cannot stay there without your hand holding it that means your stand is your
            • Segment 26: 30:00 - 32:30 hand okay so after that use the table then you write in point formula how will you vary the independent variable how will you measure the dependent and independent variables what things do you use meter rule voltmeter okay repeat measurement if the shape is circular or irregular say different position and average okay you could also say repeat the experiment for the same value of x to obtain more value of induced emf and average be specific because normally vague answers won't get much one okay so the analysis is straight line only don't use log or lone graph unless the equation is with exponents always use y equal to mx plus c to decide what kind of expression you
            • Segment 27: 32:30 - 35:00 want to use okay and then express the constant as the subject of your equation so instead of that in terms of gradient is negative k we must write k is negative gradient instead of y intercept is long b naught we will write v naught is y intercept e to the power y intercept okay okay discuss the relationship validity from the graph so from here what i will write is the relationship is valid if the lon v against x graph is a straight line with negative gradient because of the negative k and y in the set don't just say straight liner because this straight line doesn't pass origin now we're going to expect to get a graph like this lon v against x okay so this is the london one slot so once you have done that okay you follow this then any extra detail such as safety or precaution always think about your skin and your eyes wear gloves wear goggles if you don't know what to write just spam everything okay uh normally there could be high voltage electric shock or they could be hot objects okay so normally when you set up the experiment use plumb liner set square so basic it could be by the time you write this part or you might be thinking oh no i forgotten to say that we use a spirit level to ensure the ruler is horizontal just add just add can just add at the back anything else you can add here so they are not very strict about the actual setting does that make sense because sometimes you write already and then you go like hey i've forgotten to mention
            • Segment 28: 32:30 - 35:00 that the carbon have to be constant then you're right here no current in coil p is kept constant okay or you could even start writing here constant variable it's current in quality so different person will write differently as long as it's within the question you are okay all right so i want to look at a slightly different experiment okay just as a pivot point you see what are so many variables okay
            • Segment 29: 35:00 - 37:30 let's crop this one so i can draw on it then we can think about how would you write out this table for that particular experiment so what you can do during these few days is just go check out a bunch of experiments the different different type one the weird ones the things that you never see before you say you go shopping like you know window shopping but for question one okay so for this again i'm not going to write the whole experiment from scratch if you want to see me write the whole experiment from scratch go and watch the may the fat march 2-1 paper that i did with my friend and colleague miss ali it's available on youtube okay so here we have a trolley so they give you something that you start reading motion of a trolley on a wooden surface m here a mass m is placed on the trolley by the way this question is o n 20 paper phi 2. okay so you put a mass m here by a string mass p is attached to a trolley by a string which passes over a pulley oh we have a pulley we need to include pulley in drawing and then we need to also have mass p in drawing so when i read the question during exam i will immediately begin a circle or this thing one this is mass m this is mass m okay boss trolley is initially at rest okay so i gotta make sure that there is no force on release meaning i don't push the trolling student investigate how the speed be oh no so speed v means this one i need to measure figure out how to measure v speed v of a trolley at the distance d okay so this one i also need to measure
            • Segment 30: 35:00 - 37:30 you see we are harvesting this all this thing and talk about how to measure this how the speed v of the trolley at the distance d from the initial position varies with m
            • Segment 31: 37:30 - 40:00 okay i see a c so the variables the dependent independent variable is v and m so purpose number one design a laboratory experiment to test the relationship between m and b okay now it's time to stare the equation okay explain how your results purpose number two can be used to determine the values of q and r and the rest is just standard stuff like you may draw a diagram blah blah blah write your instrument okay come i draw a table now so the first thing that i'm going to draw is the so this is the physical quantity so the first one that we have is v and m again it should be quite obvious which one is easy to change and which one you measure i can change the mass m that i put on the trolley 10 gram 20 gram 30 gram 100 gram 2 kg doesn't matter what i cannot change is how fast the trolley is moving okay so i'll probably so you might be thinking if i say you're worried about the poody because you cannot visualize the experiments what you can do is you can schedule i'll probably include a pulley here so there's a pulley and this pulley probably cannot stay there need to clamp clamp the pulley okay and then there's a mess p there's a string here attached and the mass p is here oh so what we are changing is the speed of the trolley after it travels through a distance d so this trolley is probably going to go maybe be a measure from the front so maybe we actually go from here to here so this is d so maybe after this your choice yeah i
            • Segment 32: 37:30 - 40:00 don't know d is obviously going to be constant okay so it will have a certain speed but now this one actually got a lot to write guys this one is way more to write than the coil thing so we have pq right the physical quantity so that's the independent the one that we change depends then we have the dependent the one that
            • Segment 33: 40:00 - 42:30 we measure because it you change the mass you change the velocity so this is mass of the trolley mess on the trolley then this dependent is velocity of the trolley v okay constant variable okay everything else is constant numbers yes q and r you don't write law because you put q out here also no point you know what qr is if you don't know what q and i is how we're going to keep them constant what else is inside your your equation we have done v we have done m we can't do q and r because we actually have we actually have to find them unless you are god you can't change the acceleration of gravity so what else do we have we have to keep d constant the distance traveled by the trolley distance traveled by trolley d and then is p that what is p again oh mass p this mass that we hang on the pulley but of course we need to keep the mass p constant because you put different mass the trolley will accelerate differently so we all know this okay so i think we are satisfied everything in the equation is more or less accounted for if the other things that we think should keep constant we can write later okay so how to measure so we all know how to measure master we use a top pan balance the one with the digital scale one so it's not no problem velocity how to measure velocity a velocity meter no such thing what is a velocity meter [Music] so if you want to measure the velocity of something what you could do and you don't know then here's a handy dandy list to refer
            • Segment 34: 40:00 - 42:30 to average velocity or acceleration you probably need to measure time and displacement of the object and use the relevant equation of motion okay so this trolley is accelerating means how you know the trolley is accelerating dude the trolley is initially at at rest so the trolley is initially at rest it means that the trolley has to be accelerating otherwise it won't move and you won't have an experiment okay so if i think about this
            • Segment 35: 42:30 - 45:00 or rather let me draw the trolley for you trolley is here and after a certain time t the trolley is here so i can measure this distance d using a meter rule and then i can obviously time the trolley t so obviously velocity is not distance over time wire because acceleration is not zero at least i hope your kinematics are okay so then how do we find velocity we would have to use v square with we don't have the acceleration so we use the equation with no a s is equal to half u plus v times t right but this is d the distance traveled u is 0 we are looking for v and the time t can be measured so then from here v will be equal to 2 d over t so all this back of the napkin calculation you have to include the equation so we'll measure d d is also here needed but d is measured using meter rule and t is measured using a stop watch you want to be fancy people you can use a light gate you can even video and review frame by frame okay the more important thing is you calculate v as 2d over t so these are just how to measure and all the extra details again you can always refer to this one because if you look here if i talk about anything that is traveling movement involved while measuring you can view video playback frame by frame you can repeat the measurement and average but the repeat one we can write it all right so velocity is done this is done i think
            • Segment 36: 42:30 - 45:00 distance d is pretty straightforward we measure using a meter rule and mass p cap constant just use by the same mass time and time again okay so i think we can write the experiment already
            • Segment 37: 45:00 - 47:30 so when writing out this one again we start off with the statement the problem statement so let me write down first oh no wait we also need to modify the equation to get a straight line okay let me steal the equation again from the question paper [Music] where is the equation okay i'm gonna linearize this equation okay how to linearize first things first identify your variables that you measure and you keep constant so your independent dependent variables are highlighted so basically if you do the experiment you don't have to draw the table when you write out your experiment but for some students it helps their brain so maybe you have mass in gram you change change different mass and then you measure the time dot dot and after that you can find the velocity of course we can't plot m against v because it doesn't look like a straight line so what to do i don't know what to do at cross multiply we want to linearize the thing so here it will be 2d pg minus q is equal to v square m plus r so i need v to be on one side and m to be on another side normally like normally when we do experiment the top part here let me zoom in a bit normally when we do experiment the top part here would be the dependent variable so something something v v square one over v square and then whatever that is here is normally the independent variable so it's easier to measure so to help
            • Segment 38: 45:00 - 47:30 your brain i'm going to move the v square one side cannot i i exchange place uh oh yeah so basically right now i have one over v square is equal to uh this one can be m plus r okay over 2 d p g minus q once again i bring the p
            • Segment 39: 47:30 - 50:00 2 d over now i have to isolate the m i have to isolate the m so one over v square is equal to m over two d p g minus q plus r over over 2d pg minus q if your m is not sufficiently isolated for your brain i will write another line for you this will be m big bracket 1 over 2d pg minus q then this is the whole thing what is important is now you can take y is equal to mx plus c or rather x times gradient plus y-intercept okay so this is your gradient this whole this whole one over this whole thing this whole thing is your gradient okay and this whole thing is your y-intercept means they want us to find q and r yes so from here we need to modify a bit and to make my life easy [Music] i'm just going to let the gradient be equal to g so from here i can say that g is equal to 1 over 2 d p g minus q when i rearrange to find q this is such a see exponents are nicer [Music] anyway we're gonna we're gonna soldier on so what we have is 2d times g and then we will have pg i'm going to open up the bracket okay so minus 2d times g if i bring up and multiply 2dg times q this is equal to one we throw this one one side low two d g p g capital g is gradient now is equal to one minus a one plus two maybe i should flip it the other way
            • Segment 40: 50:00 - 52:30 my bad this one will be minus one i exchange blazer what i'm trying to do is i'm trying to isolate out this cue can i change color now one note are you okay am i allowed to change color give me a sec and open again one note cannot deal with linearizing equation where we were looking for q q it's just algebra guys don't worry about it so these two d g p g is here minus one and then the other side you will have two d g q okay now you can write q already your two dg don't go and cancel that cannot cancel if can cancer i also cancel already pg minus 1 over something like this don't bracket also nevermind okay so if you want to substitute gradient as something you can or you can keep writing this one as gradient gradient gradient gradient gradient we're going to repeat the same thing again for y-intercept because once we find q in such a pain we can now find the y-intercept i'm going to let the y-intercept be equal to c okay so c will be equal to r over 2 d p g minus q the good thing here is we already have q so we just need to find r so r is equal to c y intercept times 2 d p pg minus q okay the n [Music] q is found by from this equation where g is the gradient yeah so don't be fooled by thinking that oh i'm more familiar with this equation dude you don't know when you want to linearize this one whenever there's a fraction it's always a slight slight slight heading let's check out the max
            • Segment 41: 50:00 - 52:30 scheme because this is obviously not the only straight line graph you can draw there are many many types of questions okay and there are also many types of suggestion so by the way these two expressions will work so i have already found q and r
            • Segment 42: 52:30 - 55:00 which is the purpose of the question so what graph do we plot i'm going to plot a graph of 1 over v square against m and then you can say the relationship is valid if the graph is a red line with y-intercept that doesn't pass through the origin so normally this is a one mark then you find your q and r correctly uh actually this one can simplify a bit like if you want to q will be the two dg2 dg will cancel so it's pg minus 1 over 2d times gradient this part or this one this is a one one of the analysis mark you find r this is the analysis map okay like that lah so how would the mark skin look like we now have to bring all of this together so all of this uh it's like you know before you fry rice you chop up all your ingredients and people don't see your prep this is all the prep of course how quickly you do this depends on whether you can it looks a bit slow because i have to narrate every step but hopefully with basic algebra you are okay if not then it's a cost of one two three [Music] four bucks this is the okay let's look at the answers so first step we are going to define the problem right so think about your p so normally i would say problem statement or defining the problem or something like that because i like to follow the mark scheme because i know the examiner is looking at the mark scheme and if they look at the mark scheme and i make their life
            • Segment 43: 52:30 - 55:00 easy they will make my marks easy or at least that's what i think okay so the sentence makes sense so the first one when you define the problem you say m is the independent variable and v is a dependent variable done
            • Segment 44: 55:00 - 57:30 all right keep p constant do i say keep p constant oh yes keep p constant yay so i got two marks you know what to prevent myself from needing to scroll up scroll down and giving everyone including me some motion sickness i'm just gonna crop this whole thing plant it up here so we could refer to it hey i'm gonna briefly cover the equations there but i think you get my point okay so now we need to think about diagram how do you think your diagram will look like we need to have a pulley right and then we need to have the whole set up so here's how my diagram would look like i would draw the surface of a table hopefully you draw with ruler okay so this is the wooden surface okay i'm going to draw the pulley so i would label this one is the pulley actually i should draw with pencil right so i can change color and then it will look easier but i prefer to pretend i'm doing this in the examiner where i only have pencil okay and then they put a wooden surface right so i'm just going to draw another extra wooden surface on the bench just give me a sec so [Music] and then to differentiate things i will make sure i label so this one is the bench this is the wooden surface okay well so we need we need a trolley great so my i'm the kind of student that will forget to label things one so i will draw and i label at the same time trolling then we have the mass
            • Segment 45: 55:00 - 57:30 m on top of the trolley right so here is mass m then we need a string string string string string string to the pulley string string string here tie this one here this is mass p okay we also need to talk about
            • Segment 46: 57:30 - 60:00 distance d so i don't know maybe here so here to here is the any kind of distances or length that you measure should be able to indicate on the diagram okay um so in order to see it immediately right you imagine you do this experiment now what are the limitations that you encounter will be like hard to determine when the trolley passes through this so what you would normally do is you would do some marking right so what i'll do is i'll mark here so i'll just label here marker on the wooden surface okay i think i'm good okay uh an extra thing about measuring time this timer means if i want to measure like if i want to draw the light gate how do i draw the light gate right so you don't laugh but i show you how they draw they are like it by day i mean ciela how does cambridge draw they are like it here is the paper of fatwatch21 paper52 okay i have recorded a discussion about this go watch live okay so here this is how they draw light gate guys look at their light gate just just look seem to sell like it so in physics it is not it doesn't matter whether it's pretty or not the important thing is that you have to draw the light gate but of course then you can say misa if i draw the light gate here the light is floating there i need to clamp the light gate correct law so if this is you what i'll do is i would draw two light gates here i'm going to zoom in a bit okay and then i will clamp the light gates something like this please make sure you're and then i have to move the label
            • Segment 47: 57:30 - 60:00 for dila please make sure your stand looks like a stand now okay so these are my clamps for my retort stand this is d as you can see i come and really not good at drawing but it's enough so here are the hacks that i learned as a student now we thought stan can always draw last maybe in real life you will need a rod love but the stand can always draw last or you can draw a bigger
            • Segment 48: 60:00 - 62:30 diagram okay so this is my record stand label stand okay i think i'm more or less satisfied if you want to you can draw a ruler here but i will just casually mention that the ruler is you draw marker already ma i can measure a distance between the marker so i don't need to clamp the ruler oh light gate like it did my label like it light gates so if you have a habit of doodling you can do this for a few experiments so you get a hang of it please use ruler okay i don't have ruler so i now draw things like a like a potato but you should be able to use ruin and draw something a bit nicer by the way um if you do this exercise for a few questions you will you can more or less know and then you check the max schema like what i'm doing okay i'm satisfied with my diagram let's see whether i'll get marks the next part is the method mark so this method mark right by the way basically the whole idea is one line one matlab okay so let's see label diagram of workable experiment including p attached to a string so you must have all of this okay i got p attached to a string string passes over a pulley yes supported pulley i use a g clamp because i want to clamp it to the surface of the table okay string horizontally attached to trolley i guess correct trolley is labeled p is labeled i even label mass m okay i got one mark next determine v so you see light gate attached to timer to measure v so the light gate right is actually okay if you don't know how a light gate looks like
            • Segment 49: 60:00 - 62:30 all these boxes physicists draw but they never show you irl which is a bit sad hang on so a light gate looks like this okay so you see this this connecting device uh we can put this inside a inside a computer and a computer can calculate velocity for you
            • Segment 50: 62:30 - 65:00 so what we do is when we want to find the velocity of something let's say this is your trolley we will stick the card on the trolley and then we allow the trolley to pass through the light gate the trolley will start timing here will stop timing here if you start timing here and you stop timing here they will find the average velocity the device itself the computer itself will be able to find that velocity okay so generally that's how it works we connect this to a computer or a cro which they are not showing me right now something like this there's a device one now you can press through different modes okay so these are all light gates so you want to use like it can motion sensor connected to data logger can thicker timer tape also can but this one all are not very common that you use in the lab i write about something that you used before measure d and t with timer or a stopwatch or a light gate to timer so my time my light gate is to measure time okay if you want to use the light gate to measure speed your setup will look something like this one you want to use like gate to measure speed you must include a card on top so if you try out this experiment from fat much to one see mister the equation okay yeah i'm just going to go to are you see they find velocity using length divided by time and the length of the cut is coincidentally also 5 cm it's not conspiracy that's a standard like it i see i'm just sticking on the trolley
            • Segment 51: 62:30 - 65:00 but my problem with the light is that you need to stick the car and they need to put the mess and i want the mask to be as center as possible so the car has to be into the back and i don't know whether i could align the light gate so i i have a i don't know but it's fine i don't think they care about that level of detail so put it like put the card here okay and then let me go through the light kit so this is an example of i'm gonna just put this here how you would change the drawing a bit if let's say you want to use the light gate to measure so what we'll do is this is your trolley instead of your glider you put a trolley
            • Segment 52: 65:00 - 67:30 here so this is light gate to measure v this is like it to measure t okay all right let's carry on either way la or okay use a balance a top pan balance to measure m net ah measure m measure dt or all this might also get okay and then finally measure d with a ruler of course that d with a meter rule statement can already just a statement d is measured using a ruler okay you are done for method four marks four marks not that hard if you know that you have to write these things and that is how i generally suggest people do just harvest the equations and put stuff there all right here are additional details generally my advice with additional detail is you gotta you gotta think about again you are doing the experiment what is going on so first thing first think about safety what waka accident could happen maybe mass p will fall on your leg okay law to prevent trolley from falling use a cushion the sandbox barrier for the trolley now if you see people do explosion experiment they will put an entire barrier to enclose here or you could just draw a sandpit here sand pit so this is what i mean by oh i want to talk about a cushion okay okay keep d constant yes use large distances for d so that the trolley have enough distance to set to accelerate okay method to keep d constant hey marking starting at n position i just did that okay v is equal to distance over time for appropriate small distance on thicker tape
            • Segment 53: 65:00 - 67:30 distance between light gate okay or you can use 2d over t if t is the total time measure okay so when they say total time measured means you let go of p you start your stopwatch so it depends on the sentence okay so uh from for me if i'm going to use 2d over t
            • Segment 54: 67:30 - 70:00 i would say i actually would just not use one of the light gains but can so just i'll just add a label here starting position so what you could do is your first option is when you let go of mass t you start the timer by the time it reaches the end position you stop the timer or you could allow the trolley to travel a certain distance then only you start timing so they are both okay hope that makes sense okay so if it's distance between the light gate then after trolley begins moving then canada but this is just average velocity okay method to ensure the wooden surface is horizontal use a spirit level why yes because the surface have to be horizontal this wooden surface did they mentioned here i think they did or from here it's pretty obvious that it's horizontal if you don't mention this it's okay you don't need all 10 marks maximum marks you can score is 6 only okay for the same mass repeat experiment to find average of v so this this one every question can write one but your sentence must look like this for the same independent variable repeat the experiment to find the average dependent variable so you must change it depending on the experiment okay this one is the equation i got this equation remember uh i crop that later we go and compare okay so if you show this you get one mug long relationship is valid if it's a straight line
            • Segment 55: 67:30 - 70:00 not passing through the origin okay or with a y intercept method of attaching mass m to the trolley for example use tape or adhesive putty yes stick the mess on it so out of these 10 marks you only need six to score full mark but if you don't get any of these four marks it will be a minus one because your experiment totally cannot
            • Segment 56: 70:00 - 72:30 work okay or if you don't list down your variable you can't even start your experiment now i said why are we here i don't know what are we measuring i don't know okay the last four marks are in the calculation so i'm going to paste the equation here and confirm do i have the equation oh there here c c c okay so the equation here is your d one so there's there's five marks in the calculation okay and then later on if you talk about method of analysis this is our method of analysis it says put a graph of one over v against m or m against one over v can i i i chose the first one now all right so q is pg minus 2d times gradient on that here this one i already let gradient be gimma that yeah i let gradient bg okay then oops move this one here a bit and then your r is y-intercept where's my r 2d times pg minus q times y-intercept there here r is y-intercept times student okay done so this is what i mean by just because the equation looks simple it doesn't mean it's simple just because the equation for exponent doesn't mean it's hard uh what kind of equation you will get and what kind of cell you will get because unfortunately they don't let you choose experiment so you have to know everything i'm sorry and i don't think there's a proper way to guess this because the variables are just way too many we are not asking you to set up the experiment we're asking you to write a recipe for the experiment all right so that's what i think about question one
            • Segment 57: 70:00 - 72:30 are we okay people at home let's if we move on to question two i think generally right for this question the way to do it is just practice like the way i did with the two questions just now just go through this process sketch this one out write it down and then after that you go and double check the maximum it's the point that i think about all there and the i miss out on anything after a few times of that practice you should be okay and if you want to you can draw a diagram just to
            • Segment 58: 72:30 - 75:00 amuse yourself all right so that is question one in a nutshell this one is from on 20 paper phi 2. um don't worry about the kind of equation that you will get because you don't know so just list down the physical quantities think about how you're going to measure them if there's any physical quantity you don't want to measure there's a list here i also want to highlight the fact that there is one that they kind of like to ask a lot which is using the whole probe so please know the difference between hold probe and induce emf induced emf is due to the change in magnetic field whole probe is measured magnetic field so one is to measure one is measuring change and one is measuring existence so there are two different things so go ahead and check out the whole probe experiments okay i'm going to use the final the remaining time if you have no questions to move on to question two so i'm gonna keep this one here this is q1 it's not a new one as usual all of this will be at where you normally find your notes now okay don't worry too much about copying just focus on asking questions and making sure you understand all right so p2 now so for paper 2 this one is data analysis and normally you also don't know what kind of equation they give you we can give you anything but i think the key skill that you need to have is again linearizing the equation and also to find
            • Segment 59: 75:00 - 77:30 y intercept gradient certain constants and also certain technique about drawing graphs all right so before i go on i just want to point out that there are a few things that you probably if you don't read you probably don't know how to do now hall probe is one okay uh although i think karen you can read on the cro so there is no problem wavelength of light you use the young double slit or diffraction grating or you use filter led if you decide to use the young double slit or diffraction grating to find the wavelength of your light check out these experiments then you must include the exp the relevant equation i think volume all this is okay angle all that no problem force use a newton meter pressure use the monometer this one now when this one came out everyone lost their mind because no one expected pressure in winter 18. go check out the question but the rest these are all the standard stuff the special ones are pressure when read that one force and sometimes you have uh different types of force one so go and check the magen 18 paper phi one sometimes we use a top pan balance to measure the force for example the force on the magnet and the wire the your current balance okay um other things that are a bit irregular like i mentioned is wavelength of light and using the whole pro don't as you don't see coordinate immediately use whole probe okay you better you better decide that the whole probe is used to measure how strong the field is for example this one we don't use hall probe because
            • Segment 60: 75:00 - 77:30 we want to measure the induced emf this one we measure the force between two point charges this is the major 18 vapor law go and look at it okay uh so you can go through this all right and then this one you see here b is matte flux density at point p this is where we use a whole protein they even tell you uses a whole okay long so you just gotta go and this is generally right if you look at my compilation of set a and set b it should be enough for you to do most of the questions
            • Segment 61: 77:30 - 80:00 because i compile a variety like there's kinematics here and then there's some weird young modulus then got wavelength of light what this okay i will give you the yellow later then this one got ldr1 why why no eq why no diagram i got standing wave okay no so go and go through the question set a is the easier one set b is the one where i bring in all the magnets and the circuits and the alternating current what is this don't even have a drawing okay go and read read up everything but for favor 2 if you don't know it's fine just use y go the mx plus c to hack the equation here are some common uncertainties okay so generally right the first skill that you need to have is how to linearize and if you don't know there is also another more broken down version video in the playlist we'll talk about different different types of equation so generally you may get a polynomial equation like the one that we got just now you can get an exponent which is lon or e you can get a log base 10 so lg i think that's all the equation you'll get look no more already okay number two oh i mean will you get three goal sure but not the type where you need to use identity normally it's from resolution of forces so you just need to know to measure the angle this is question two okay anyway so how to linearize the equation into the format y is equal to m x plus c oh yeah basically if you do physics and you don't know how to use this equation properly your life is just hard from paper three to paper five okay
            • Segment 62: 77:30 - 80:00 number two we are still going to deal with uncertainties so case one case one is the fail safe method meaning if you don't know what identity to use and you look at the equation you go like what on earth is this how okay you just never mind you can always take half of the range so let's say half of the maximum value whatever that maximum value is that can be gradient can be y intercept minus minimum value
            • Segment 63: 80:00 - 82:30 and sometimes this is the only method that you have so this one can be used for all calculation but this is pros the cons here is it is going to be a lot of work for one mark you say you don't want the mouse okay no like everything also one mark in this question okay case two you can use identities okay so there are two types of identities that you can okay so i need to hang on let me talk about case one a bit more first there's a slight exception that uh to case one that you have to use for example sometimes they will give you we always use this for looking for uncertainty in gradient [Music] so that would be modulus the gradient of your best feed line minus the gradient of your worst fit line when watch the videos where we draw best fit line was fit line okay the second one is the uncertainty of your y-intercept we will also take modulus the difference between the best y intercept minus the worst y intercept okay next one case two when we deal we could do with identities but we can only deal with identities if let's say we know the equation okay so if we don't know the equation then you cannot deal with identity so the first one the first identity we have is uncertainty of if a is b plus c or minus c then the uncertainty of a is the uncertainty of b plus uncertainty of c the more measurements you take the more uncertainty you have okay the second case if a is equal to b
            • Segment 64: 80:00 - 82:30 squared times c divided by d power three i don't know whatever this value is this one we must use fractional or percentage uncertainty so the percentage uncertainty for a is
            • Segment 65: 82:30 - 85:00 the percentage uncertainty of b because when you calculate a you measure b but two times because you square the b okay plus uncertainty in c over c percentage uncertainty plus three times the percentage uncertainty of b okay so this one can useful third one lock and lawn and put a star here there's a video where we derive this equation but right now at the if of exam ain't nobody got time for derivation so if for log and lon if let's say right you really don't know the actual identity it is perfectly fine to just operate on maximum and minimum values okay it's perfectly fine there's no problem with doing that but if let's say you actually know the identity then you can use it so if log well let me think a bit because currently i cannot remember the identity but sometimes i also will have to use the max mean value let me go and take the notes a bit because i don't have my paper 5 with me now [Music] lock and lawn okay so half range always can okay so here's the identity if y is equal to log a to the power of x so in case you don't know what this one is uh this is your base this is your number right let me pull out calculator to x where is my calculator okay here is my handy dandy calculator so when you type this into your calculator it's log base 10. this one this one your calculator is ten this is ten then where we put num inside here is the number
            • Segment 66: 85:00 - 87:30 so that would be it's not long your calculator only got two mode that is available to you at this setting okay you either log let's say you log eight la so the one is not 10 8 so a is 10 and x is eight okay another one that you have is this one see so you can put 10 here and then you can put eight here and then i go and minus this one just to show you they are the same thing log eight we're going to get zero because it's the same thing okay these two are the same thing so the other one that you have is lon [Music] lon is log base e okay so log this one is normally written as this or this log base e we don't write log base e one ma we write lon wherever it can be eight eight 8 it can be 4 4. okay so whenever we have this format right if you want to find the uncertainty there are two two outcomes okay the uncertainty of y which is now the uncertainty of log a times x this uncertainty is equal to 1 over lon a uncertainty in x over x okay the derivation is in the playlist if you want to know if you don't want to know you can just use only but it will not be given in the exam okay so this a is your base so let's look at the first case if a is equal to 10 because this one a equal to 10 this whole line here a is equal to 10. so if a is equal to 10 then your uncertainty
            • Segment 67: 85:00 - 87:30 of log x because 10 becomes log x will be equal to 1 over lon 10 uncertainty in x over x means got log question came up before god next case
            • Segment 68: 87:30 - 90:00 if a is equal to exponent then the uncertainty of lon x will be equal to 1 over lon e times uncertainty in x over x but one over lon e is one so this one would be uncertainty in x over x so you have this and you have this can um depending on the question no different question is different math right so the whole idea here is you should follow the general rule of thumb if you know the identity you can use them if not you can use maximum minus minimum let's look at an example okay this is log base 10 right so what you're going to do is you're going to press log but you want to check out the exponents you see this part here the exponents are not inside meaning you when you look right this one should be log one two nine times ten to the power of six meter because now this one is in meter all right compare these two let me check compare this to the other one where your table is like this this is the the question from on 16 paper phi 2. i'm going to take out the question compared to this table here
            • Segment 69: 90:00 - 92:30 you see this one they put the prefix inside hi this one this one here this one the prefix is not inside so you should press this one this one the prefix is inside so when you press calculator it should be log 630 means why they do this to us i don't know i don't know but be careful uh look look they are not consistent one i mean it's a different thing so if you want to try this question this is from on 16 paper phi 2 and if you want to try out this question here this one is from i think all of this is in the set a set b o n 11 paper phi 2. okay so you press your calculator you should be able to this one you use the prefix so this one is 8.111 okay second thing about this is this one is 3 sf so this one when you transfer over to here it has to be this is very weird this will be same dp so this must be 3dp or 4dp so normally right when we transfer values okay let's say we look at a table that is not locked and lonna just a regular old table let me go and find another one okay maybe maybe this one [Music] so this one you 1 over a this is 2 sf so this one is 2 to 3 sf
            • Segment 70: 92:30 - 95:00 2 sf 2 to 3 sf 2 sf 2 to 3 sf this is a standard one that you always do you know because normally i will just tell you this one is a calculated value so we look at the sf of the original value let me transfer but for lock is a special special cookie not only prefixes can play hide and seek with you sometimes it's inside the lock itself so that for example this one you will press block 630 press my calculator 6 3 0 and that would give you 2.79 so this is 3sf so this one should be 3 or 4dp we go from sf to dp which is very weird only for long so this will be 2.799 i can put 799 or i can put 2.80 0. this is 3dp 0793 okay so in a nutshell when transferring dp and sf for everything else we will follow the lease sf or plus one everything else for lock or lawn lon we will follow the sf but it will become dp or plus 1. so example log 630 will be equal to 2.799 or 2.7993 this one is 3 sf so now it's 3dp or 4dp okay this is the part that is confusing the other parts are pretty standard it's just that for log and loan
            • Segment 71: 95:00 - 97:30 they have a special way for you to find the uncertainty there's also a special way for you to calculate the value for how many dp and sf to pull up basically okay so one last thing if let's say you are asked to find the uncertainty for example for v okay so you have two choices let's look at the first one um let me do log 1.9 so this value here again this is 2sf so i reach here i can take 2 to 3dp let's say i stick to 33dp this is 2.0.279 okay so 2sf then which here 2sf transfer here would be 3dp from here 2 here okay this one three sf transfer here 3 to 4 dp okay let's talk about uncertainty plus minus you have a few options for this one you can either take log you want to do half the range can 1.9 plus 0.1 2.0 minus log 1.9 minus 0.1 1.8 divided by two can option this is half the range option two use identity one over lon 10 0.1 over point nine mr answer the same i press number one [Music] you can press another one if you want and divide by 1.9 this is two i mean i'm just going to take one sf but i guess i can take another one just for comparison purposes wait this is a bit wrong sorry right wrong needle this is lon 2.0 minus log
            • Segment 72: 97:30 - 100:00 minus log one point eight so max minus min not two minus log one point eight divided by 2. i get 0.02 3 as well so it's higher it's up to you la some student [Music] this is fast the bottom one is faster because you don't have to go through the mental arithmetic of 1.9 plus 0.1 and 1.9 minus 0.1 because sometimes this uncertainty will be some weird number like 15 4 and 8. gg so this one this uncertainty hall will be either log 28 minus log 20 divided by 2 or 1 over lon 10 bracket and 4 over 24. so you just take this one here but this one it's only about this one and there's always one to one on ten four there by 42 eight different one five four eight direct three zero four this is faster this is slower this is i guess you always know like half the range so totally up to you this one can be a mixture of sf please practice paper too things like drawing best fit line finding absolute uncertainties finding uncertainties for things okay um we already recorded the fat march 21 paper so you can try out the paper first and then come back and compare and say and compare methods practice at least five different style of tables so if you do one log and then you do another lawn one then maybe you find one with angle one there's one so all the set a set b should be enough there is one particular one in set bead i want to point out this is a slightly anomalous case okay so for set b you see this one this one
            • Segment 73: 97:30 - 100:00 got log which is okay and t and you see here include absolute uncertainties in t and in log t and s so they need absolute uncertainty here i also need absolute uncertainty here
            • Segment 74: 100:00 - 102:30 so sometimes students is confusion this one got absolute uncertainty back got half the range so the uncertainty for this is half the range of these two numbers okay let me explain to you what i mean the uncertainty for this there's a certainty for this one you see how this is t and based on the question i think it's 10 oscillation yeah so you see it's going to oscillate up and down this t is time t for 10 oscillation so you are asked to find the period okay so to find the period what we are looking for is the the average of these two average of these two is 1.56 i mean 15.6 okay and then after that this one will be 1.564 because this is 10 t so 1.56 and then what we'll do is move plus minus plus minus here you need to do the maximum minus minimum so 16.0 minus 15.2 divided by 2 this will be 0.4 okay but this is for 10 cycle this t is one cycle so this will be 0.04 okay i repeat again everything else so if they give you plus minus that is great if not then you have to include your own but the good thing here is i think all the range is 0.8 see 0.8 0.8 0.8 3 and 11 0.8 3 and 5. so 0.8 so the difference is 0.8 we want to find the uncertainty will be half of the difference between maximum and minimum value so what i'm doing is uncertainty in t the small t will be equal to t max minus min divided by 2.
            • Segment 75: 102:30 - 105:00 okay so hence the uncertainty for period will be the uncertainty for 10 cycle divided by 10. okay then you go and lock this one now just make sure you always check the bracket hey s and s okay so no need to worry about prefix in fact 1.56 only two prefix okay so that's generally what i want to focus on in question two for this session so this is not enough you need to go and spam do some questions uh and see whether you can finish on time and get familiarized with the paper it's not a very hard paper it says do you know your experiments or not and do you know what to do when we give you some data and ask to plot the graph and find the gradient and the y intercept okay so all the tips you can find in the discussion recording for fat march 2 1 question 2 right so that's it for paper 5. just stay calm my general strategy for students is do the question you are most comfortable with first whether it's one or two but be aware that sometimes uh don't spend too much time in one question unless you don't know totally do not to do the other question which is what i hope will not happen so i will okay so that's it for paper five just go through your weaknesses whether it's question two time management or finding uncertainties cover a range of different types of questions okay and also whether it's paper one designing the experiment learning to curate all the information inside a table format to help you organize your brain learning how to linearize and also learning how to draw diagrams okay so hope this is helpful to you stay calm stay cool
            • Segment 76: 102:30 - 105:00 i'll see you because i won't see you anymore will i all the best for your a levels and in your life you've been doing very well so far trust yourself one thing at a time and it's not easy to study online alone at home just so you know that you are doing great okay peace out bye