Physics 9702/52 May/June 2022: question paper and mark scheme
Cambridge AS & A Level Physics (9702), Paper 5 Planning, Analysis and Evaluation, May/June 2022. Read both free below, or download them. Done the paper? Get it marked by AI against this mark scheme.
Two parallel cylindrical conductors each have a small cross‑sectional area A. A thin metal bar connects the two conductors, as shown in Fig. 1.1.
L
area A
C
cylindrical x conductors metal bar
C y area A
Fig. 1.1 (not to scale)
The metal bar has a square cross‑section with sides of length y. For each conductor, the distance between its end C and the centre of the metal bar is L. The distance between the centres of the conductors is x.
The ends C are connected to a power supply and the current I in the conductors is measured.
It is suggested that I is related to L by the relationship
E 2PL Qx
= + 2
I A y where E is the electromotive force (e.m.f.) of the power supply, and P and Q are constants.
Plan a laboratory experiment to test the relationship between I and L.
Draw a diagram showing the arrangement of your equipment.
Explain how the results could be used to determine values for P and Q.
In your plan you should include:
● the procedure to be followed
● the measurements to be taken
● the control of variables
● the analysis of the data
● any safety precautions to be taken.
Diagram
…… [15]
Mark scheme
1 Defining the problem
L is the independent variable and I is the dependent variable or vary L and measure I 1
keep E constant 1
Methods of data collection
labelled diagram of workable experiment including: 1
circuit diagram with power supply connected to ends C
ammeter in series with power supply and conductors
correct symbol for ammeter and power supply
circuit diagram with voltmeter correctly positioned to measure E across the power supply 1
use a rule(r) to measure L and x 1
use a micrometer/calipers to measure y 1
1 Method of analysis
1 1 1
plot a graph of against L or equivalent (e.g. L against )
I I
(Do not accept log graphs.)
gradient × AE 1
P=
2
1 AE
(for L against : P = )
I 2 × gradient
y -intercept × Ey 2 1
Q=
x
1 y -intercept × 2Py 2 y -intercept × Ey 2
(for L against : Q = − or Q = − )
I Ax gradient × x
1 Additional detail including safety considerations 6
D1 do not touch/use (heat resistant) gloves to avoid hot conductors/metal bar
or
use a protective resistor/small e.m.f. to reduce the current
or
switch off when not in use/when moving bar
D2 keep A and y constant
D3 keep x constant
D4 use of micrometer/calipers to measure diameter of conductor and A = πd2 / 4.
D5 repeat measurements of diameter along conductors/different (perpendicular) directions/different points and average
or
repeat measurements of y in different (perpendicular) directions/different points/along bar and average
D6 method to ensure that L is the same for each conductor, e.g. check both lengths
D7 method to determine L e.g. measure to edge and add y / 2
or
method to determine x e.g. measure between the conductors and add diameter
D8 method to keep x constant with reason, e.g. adhesive/plasticine/blocks (one either side of each conductor) to prevent
cylindrical conductors from moving
D9 method of ensuring good electrical contact, e.g. clean metal bar/cylindrical conductors or use of solder or crocodile
clips to connect circuit to the conductors
D10 relationship valid if a straight line is produced (not passing through the origin)
The brightness of some stars varies regularly. These stars are called variable stars.
Fig. 2.1 shows the variation of luminosity with time for a variable star.
period
luminosity
time
Fig. 2.1
A student determines the period T and mean luminosity L of the star.
The student repeats the process for different variable stars.
It is suggested that L and T are related by the equation
L = SKT a
where S is the luminosity of the Sun, and a and K are constants.
(a) A graph is plotted of lg L on the y‑axis against lg T on the x‑axis.
Determine expressions for the gradient and y‑intercept.
gradient = ……
y‑intercept = ……
[1]
(b) Values of T and L are given in Table 2.1.
Table 2.1
T / days L / 1030 W lg (T / days) lg (L / 1030 W)
22 2.9 ± 0.2
32 4.9 ± 0.2
42 6.9 ± 0.2
54 9.8 ± 0.2
78 16 ± 2
97 21 ± 2
Calculate and record values of lg (T / days) and lg (L / 1030 W) in Table 2.1.
Include the absolute uncertainties in lg (L / 1030 W). [2]
(c) (i) Plot a graph of lg (L / 1030 W) against lg (T / days).
Include error bars for lg (L / 1030 W). [2]
(ii) Draw the straight line of best fit and a worst acceptable straight line on your graph. Label both lines. [2]
(iii) Determine the gradient of the line of best fit. Include the absolute uncertainty in your answer.
gradient = …… [2]
1.5
1.4
lg (L / 1030 W)
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 lg (T / days)
(iv) Determine the y‑intercept of the line of best fit. Include the absolute uncertainty in your answer.
y‑intercept = …… [2]
(d) Using your answers to (a), (c)(iii) and (c)(iv), determine the values of a and K. Include the absolute uncertainties in your values. You need not be concerned with units.
Data: S = 3.85 × 1026 W
a = ……
K = ……
[3]
(e) A variable star has a period of 5.0 days.
Determine the luminosity L of this star.
L = …… W [1]
[Total: 15]
To avoid the issue of disclosure of answer‑related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge
Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cambridgeinternational.org after the live examination series.
Mark scheme
2(a) gradient = a 1
y-intercept = lgSK
2(b) 1
lg (T / days) lg (L / 1030 W)
1.34 or 1.342 0.46 or 0.462 ± 0.03
1.51 or 1.505 0.69 or 0.690 ± 0.02
1.62 or 1.623 0.84 or 0.839 ± 0.01
1.73 or 1.732 0.99 or 0.991 ± 0.01
1.89 or 1.892 1.20 or 1.204 ± 0.05 or 0.06
1.99 or 1.987 1.32 or 1.322 ± 0.04
Values of lg (T / days) and lg (L / 1030 W) correct as shown above.
Absolute uncertainties in lg (L / 1030 W) correct as shown above. 1
2(c)(i) Six points from (b) plotted correctly. 1
Must be within half a small square. Diameter of points must be less than half a small square.
Error bars in lg (L / 1030 W) plotted correctly. 1
All error bars must be plotted. Total length of bar must be accurate to less than half a small square and symmetrical.
2(c)(ii) Straight line of best fit drawn. 1
Points must be balanced. Do not accept line from top point to bottom point.
Line must pass between (1.43, 0.60) and (1.45, 0.60) and between (1.84, 1.15) and (1.86, 1.15).
Worst acceptable line drawn (steepest or shallowest possible line that passes through all the error bars). 1
All error bars must be plotted.
2(c)(iii) Gradient determined with clear substitution of data points into Δy / Δx. 1
Distance between data points must be greater than half the length of the drawn line.
Gradient of worst acceptable line determined. 1
uncertainty = (gradient of line of best fit – gradient of worst acceptable line)
or
uncertainty = ½ (steepest worst line gradient – shallowest worst line gradient)
2(c)(iv) y-intercept determined by substitution into y = mx + c. 1
y-intercept of worst acceptable line determined by substitution into y = mx + c. 1
uncertainty = y-intercept of line of best fit – y-intercept of worst acceptable line
or
uncertainty = ½ (steepest worst line y-intercept – shallowest worst line y-intercept)
Do not allow methods using a false origin.
2(d) a = gradient = (c)(iii) and a and K both given to two or three significant figures. 1
Value of K determined using y-intercept. Correct method must be seen. 1
10 y -intercept × 1030 10(c)(iv) × 1030
K= =
S 3.85 × 1026
or
K = 10 y -intercept −lg S × 1030
or
26
K = 10(c)(iv)−lg 3.85×10 × 1030
absolute uncertainty in a = absolute uncertainty in gradient 1
and
ΔK =
(10 y -intercept
)
− 10 WAL y -intercept × 1030
S
Correct substitution of numbers must be seen.
2(e) L determined from (d) or (c)(iii) and (c)(iv) with correct substitution and correct power of ten(s). 1
Do not accept incorrect POT for a or K.
L = 3.85 × 1026 × (d) × 5.0(c)(iii)
or
lg L = (c)(iii) × lg5.0 + y -intercept
Checked your answers against these? Let AI mark the whole paper, on your own working.
Examiners follow the generic marking principles at the front of the scheme, then each question's points: method (M), accuracy (A) and independent (B) marks, error carried forward where the scheme allows it, and positive marking, so you're credited for what you got right.
Check your answers against it
Done this paper? Upload your script and CIE Buddy's AI marker marks it question by question against this exact scheme, puts the ticks on your own working and says what each lost mark needed.
Where can I find the 9702/52 May/June 2022 mark scheme?+
On this page, free: the mark scheme for AS & A Level Physics 9702/52, May/June 2022 (9702_s22_ms_52), and the question paper (9702_s22_qp_52), to read or download, with each question's marking points written out underneath.
How many marks is 9702/52 out of?+
Physics 9702/52 for May/June 2022 is out of 30 marks, with 1 hour 15 minutes to answer it.
Can I get my 9702/52 answers marked?+
Yes. Upload your answers to 9702/52/M/J/22 as a PDF or photos, and CIE Buddy marks every question against this paper's official mark scheme, using Cambridge's marking rules. You get your score, each lost mark explained on your own script, and the topics to revise. It's a guide, not an official Cambridge grade.