• Do not panic if the context of the question appears unfamiliar to you. During your A Level studies you will have used or learnt about suitable apparatus for completing the task. If you are asked to ‘use’ any unfamiliar apparatus the question will supply you with all the details that you need to know about.
• Read the question very carefully – it may give you guidance on those aspects of your plan to which you need to pay particular attention. It will also help you to identify the independent and the dependent variables.
• When writing your answer you will need to consider some or all of the following:
- what apparatus you will use
- what experimental arrangement will be used - what procedure will be followed
- the independent and dependent variables
- the means of keeping other variables constant - use the word ‘constant’
when identifying these variables, saying you will ‘control’ them is insufficient
- how the raw data readings will be processed to give the desired result, e.g. what derived quantities you might calculate or what graph you might plot
- what relevant safety precautions should be in place
• The relationship to be tested, given to you in the introduction to the task, will suggest the type of graph to be expected. You will need to describe it as
precisely as possible. For example, is it linear, does it pass through the origin? If you choose a logarithmic graph, you will be expected to predict its slope from the
given expression.
• When writing your answer you must write down all the information clearly and explicitly - the examiner cannot give you marks for things that are vaguely implied.
• Many of the marks can often be scored by having a good working diagram (even if the accompanying explanation is weak) and so you should spend time making sure that your diagram shows all the relevant details and is fully labelled. For example, make clear the exact points, between which, measurements, such as distance, are to be made.
• The equipment and procedures that you describe in your answer should be realistic and workable.
• One mark is available for describing safe working. This must relate specifically to the apparatus being used. It is not sufficient to write, for example, ‘keep all bags and coats out of the way’.
• Additional marks are available for detailed descriptions of apparatus/techniques. There are always more possible answers than marks available, so if you write your plan carefully, then some these marks should be gained as you go along. It is not expected that you write a separate section solely for the detail marks.
• As part of your preparation for this question you should plan some of your own experiments, but this should be done under the close supervision of your teacher. Also practise answering past papers.
• A sketch graph is not necessary, but if drawn it should be consistent with your description of the graph.
Evaluating data Question
• The number of significant figures used in a derived quantity that you calculate from your raw readings should be equal in number to (or possibly one more than) the number of significant figures in the raw readings. For example, if you measure potential difference and current to 2 and 3 sig figs respectively, then the corresponding value of resistance calculated from them should be given to 2 or 3 sig figs, but not 1 or 4. If both were measured to 3 significant figures, then the resistance could be given to 3 (or 4) sig figs.
• When drawing your graph, do not forget to label each axis with the appropriate quantity and unit, using the same format for expressing column headings in a table. Choose a scale such that the plotted points occupy at least half the graph grid in both the x and y directions. The x-axis scale should increase positively to the right and the y-axis scale should increase positively upwards. Use a convenient scale such as 1, 2 or 5 units to a 2cm square as you will then be less likely to make a mistake with the position of your plotted points and it will be easier for you to read off points from your graph if you are
calculating the gradient or finding an intercept. Similarly, it is good practice to mark values on at least every other 2cm square.
• All your plotted points should be on the grid; points in the white margin area will be ignored. Plot all your observations and ensure that they are accurate to half a small square. A fine cross (or an encircled dot) drawn with a sharp pencil is acceptable, but be careful not to obscure the position of your points by your line of best fit or other working.
• When drawing your line of best fit, ensure you have an even balance of points about the line along its whole length. If it is a straight line, use a clear plastic rule so that you can see points on both sides of the line as it is being drawn.
• Show all your working when calculating a gradient. It is helpful to draw the triangle used to calculate the gradient on the graph and to clearly label the coordinates of the vertices (accurate to half a small
square). These values can then be used in the gradient calculation. The length of the hypotenuse of the triangle should be greater than half the length of the graph line.
• If you are required to give a value for the y-intercept, it may be possible to directly read it off from your graph from an axis where x=0. If this is not possible you can instead calculate the y-intercept by using the equation of a straight line. In this case you should substitute into this equation a pair of x and y values from your line of best fit along with your calculated value of gradient.
• It is particularly important that the rules, previously given for significant figures, are strictly adhered to.
• You will be expected to use the uncertainty given in the raw data to find the uncertainty in calculated data. The latter will involve a function such as a logarithm. This requires plenty of practise, if you are to be able do it with confidence in the examination.
• You will need to be able to translate the calculated uncertainties into error bars on your graph and then to draw the worst acceptable line. Again, this requires plenty of practise.
• Once the graph has been drawn, you will be expected to find uncertainties in both the gradient and the intercept – using your line of best fit and your worst acceptable line. A lot of marks depend on your being able to calculate the uncertainties in the calculated data.
• Every candidate is provided with the same data and so the final values calculated should be very similar. One mark is available to candidates who manage to work within a given tolerance, determined by the Principal Examiner.
Source:Learner Guide for Cambridge AS and A Level Physics(© Cambridge International Examinations 2012)
Hope this helps!!!
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w10_qp_52.pdf
How to do the errors part here ?> errors in log T ?
Soldier313 fb.junks
or anyone ?
for this one ...calculate the error in T values which o.2/10 = 0.02
now get the upper limit of T which is for the first one in the table lg(1.96+0.02) subtract this from normal lg value ...which is lg1.96
so lg1.98-lg1.96 = 0.004 easy peasy and so on
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w10_qp_52.pdf
How to do the errors part here ?> errors in log T ? Soldier313
fb.junks
or anyone ?
{x + delta x/2 } / { x - delta x /2} take log of whole term ...like for first box ... {1.96 + (0.2/1o)/2} / { 1.96- (0.2 / 10)/2} then take log
rafay malik said: ↑
Is it acceptable to write the answer to question one in bullet forms, under the specific headings? ( defining the problem, methods of data collection etc).
I am not sure but if it was even acceptable.The examiner will mark those points under only that specific heading only so I recommend to write in paragraphs with no headings so each point where ever
mentioned is considered.
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w10_qp_53.pdf
Q2 e part please V=V0e^-t/CR
.10Vo=V0e^-t/CR(AS 10% of original potential difference) ln(.10)=-15/CR (V0 eliminated on both sides)
Uncertainty of R=(Uncertainty of C/C )xR Assalamoalaikum
can anyone plz tell me how to find the absolute uncertainties in Q2b
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s10_qp_51.pdf
Xc = V0 / I0
So, (Error in Xc) / Xc = [ (Error in V0) / V0 ] + [ (Error in I0) / I0 ] eg for first row:
Error in Xc = { [ 0.2/5 ] + [ (0.2x10^-3) / (15 x 10^-3) ] } x 330 Error in Xc = 18
Hope that helped Javior said: ↑
does anyone know how to draw a hall probe .. should we show the plane and voltmeter or just a probe labelled hall probe?
and is it true that if you attach a signal generator to a coil you an ac current?
plz anyone ill be real grateful
...Just draw a box(label it with hall probe) and show connections to voltmeter and power supply ...or if u good at showing plane show the pplane perpendicular to field to get max voltmeter reading...and for second its true signal generator can produce ac...and we can vary frequency of ac..
Can someone please show me how to calculate the tabular values of v^2 ?
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w12_qp_53.pdf
v = s/t where s=distance, t=time v^2 = (s/t)^2
so v^2 = (0.05/t)^2
then substitute values of time from each row into the eqn eg for row 1, v^2 = (0.05/0.046)^2
so v^2 = 1.18
then uncertainty is (max value of v^2 - min value of v^2) / 2 so max value of v^2 = (0.051/minimum time)^2
min value of v^2 = (0.049/ max time ) ^2
subtract these two values and then divide by 2 to obtain uncertainty
Hope that helped
an anyone plz tell how the newtonmeter is used in finding the force b/w two charged plates in winter 2006 paper 5 question2?are there any weights added?plz explain IT'S URGENT!!
..this may be helpful. Correct me if I am wrong..
Can someone please show me the diagram for question #1 ?
http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w09_qp_52.pdf
sorry you're seeing a reply after so long! Anyway i cant post a pic,but the basics of the diagram are what is shown in the question,plus:
-a meter rule placed vertically "behind" the wire,to measure distance -micrometer to measure diameter of wire
-rheostat in circuit to keep current constant and ammeter in current
thats it!
hope i helped!
Aoa wr wb
Can someone please provide a detailed diagram and explanation for qn 1 of this paper please?
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w11_qp_51.pdf
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w11_ms_51.pdf
I'll try to upload an image later, but hopefully, for now, the explanation is okay - sorry!
The independent variable in the investigation is the field strength B at the center of the coil and the dependent variable is, then, the radius of the coil. Since the strength of the magnetic field at the center of the coil depends upon the current in the coil and the number of turns in the coil, these two variables need to be kept constant; no matter what the radius is, the same number of turns should be used (the more the coils, the greater the field strength, so it is a control variable) per coil. The current can be kept constant by placing a rheostat in series with the coil and using an ammeter to measure the current through the coil. If the current decreases, the resistance of the rheostat can be decreased to bring up the current. If the current increases (sudden surge, any other reason) the resistance of the Rheostat can be increased to bring the current down.
The experiment can be carried out by first taking a length of wire and wrapping it firmly around a cylindrical object; this will give it a coil-like shape with an approximately constant radius. To increase the radius later, a wider cylinder can be used. A ruler can be used to measure the diameter of the coil, and the result divided by 2 to get the radius. This measurement can be repeated around the coil along several diameters and the values of r averaged.
The coil can be connected to a d.c. power source, an ammeter and a rheostat, all in series (diagram) and the coil can be hung (after being flattened) from a clamp/ retort stand holder. The center of the coil can be found using a ruler, and a stack of books with a track/ruler placed on top of them can be aligned with the coil such that the ruler is perpendicular to the plane of the coil and is going into the plane of the coil.
This track can be used to move the hall probe towards the center of the coil. The Hall probe should be connected to a calibrated galvanometer/ voltmeter, and the maximum reading shown can be noted down as the value of B. Several readings of B can be taken for each radius r and averaged to plot into the graph.
About 10 readings can be plotted into a graph of B on the y-axis versus (1/r) on the x-axis. If the relationship is indeed true, the graph should be a straight line through the origin (the equation is the form of B = k/r where k is a constant, so the gradient is B * r = k, so gradient is constant).
The coil may heat up due to the current passing through it, so it is advisable to let the coil cool down between experiment before replacing it/ using heat resistant gloves while doing so.
A large current can be used to ensure a large value of B; this reduces percentage uncertainties (any that might creep into the readings) and also gives a large value of B. Similarly, a large number of coils can also be used, but kept constant throughout the experiment. Any external currents and magnetic fields will have to be eliminated, so the experiment should be performed in an isolated location. Again, the current can be kept constant using a rheostat (as mentioned above) and if the same Hall Probe setup is being used for all the experiments, the probe and voltmeter can be calibrated in a magnetic field of known strength.
Hope this helped!
Good Luck for all your exams!
when we divide quantity by something.what will be the uncertainty of new value? mj/10/52 question number two.plz someone help
If you are referring to dividing t by 10 to give T, the uncertainty is also divided by 10.
The reason is that when you multiply/divide two quantities together, you add their percentage uncertainties to find the percentage uncertainty in the resulting value.
In this case, if you want to find the percentage uncertainty in the value of T, it will be the (% uncertainty in t) + (% uncertainty in 10) = (% uncertainty in t), since 10 is a constant, absolute value which is
completely accurate and has no percentage error.
As an example, if we take the first value of t, 18.9, the percentage uncertainty is:
0.1/18.9 = 0.00529 (0.5 %).
Therefore, the uncertainty in the final answer is 0.5% = 0.00529:
The absolute uncertainty is 1.89 * 0.00529 = 0.01.
You can see that the uncertainty in 1.89 is 10 times less than the uncertainty in 18.9, so the uncertainty has been divided by 10, the same value that divided t to give T.
Hope this helped!
Good Luck for all your exams!
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w10_qp_52.pdf
anyone did the graph portion ov this one? and the errors one too obviously ?
can anybody show the graph plotted or the errors ?
Hopefully this diagram can assist you with the hall probe issue:
Question 1 of this paper
There's a bell jar with a bell inside it, If it already has a bell inside it, why do we need to provide a source of sound in form of a loudspeaker etc??!
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_nos_sp_5.pdf
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_nos_sm_5.pdf
You don't need to 'provide' a source of a sound in the form a loudspeaker. The bell is a source of sound, and that's more than enough.
A loudspeaker can be used as an additional material to make it easier for the person to hear the sound of the bell.
so mic is out side bell jar or inside it ???
"Workable arrangement Should include container, source of sound, pump, microphone, CRO"
Since this marking point is one of the methods of data collection rather than just an additional detail, it led me to assume that, we need a sound source.
So the bell is a sound source, no?
Yeah it is.
But in the variables to be controlled it also states frequency of sound source, so how do we exactly control the frequency of the bell sound ?
MJ2008 MJ2010 51 MJ2011 52
And other years I've done, diagrams have already been posted