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UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS
GCE Advanced Subsidiary Level and GCE Advanced Level
MARK SCHEME for the October/November 2010 question paper
for the guidance of teachers
9702 PHYSICS
9702/43
Paper 4 (A2 Structured Questions), maximum raw mark 100
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of
the examination. It shows the basis on which Examiners were instructed to award marks. It does not
indicate the details of the discussions that took place at an Examiners’ meeting before marking began,
which would have considered the acceptability of alternative answers.
Mark schemes must be read in conjunction with the question papers and the report on the
examination.
•
CIE will not enter into discussions or correspondence in connection with these mark schemes.
CIE is publishing the mark schemes for the October/November 2010 question papers for most IGCSE,
GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level
syllabuses.
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Page 2
Mark Scheme: Teachers’ version
GCE A LEVEL – October/November 2010
Syllabus
9702
Paper
43
Section A
1
(a) (i) rate of change of angle / angular displacement
swept out by radius
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(b) centripetal force is provided by the gravitational force
either mr(2π/T)2 = GMm/r 2
or
mrω 2 = GMm/r 2
r 3 × 4π2 = GM × T 2
GM/4π2 is a constant (c)
T 2 = cr 3
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(c) (i) either T 2 = (45/1.08)3 × 0.6152
T = 165 years
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(1)
(1)
(1)
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(ii) ω × T = 2π
or
T 2 = 0.30 × 453
(ii) speed = (2π × 1.08 × 108) / (0.615 × 365 × 24 × 3600)
= 35 km s–1
2
(a) atoms / molecules / particles behave as elastic (identical) spheres
volume of atoms / molecules negligible compared to volume of containing vessel
time of collision negligible to time between collisions
no forces of attraction or repulsion between atoms / molecules
atoms / molecules / particles are in (continuous) random motion
(any four, 1 each)
(b) pV =
1
3
1
3
Nm<c2> and pV = nRT or pV = NkT
2
Nm<c > = nRT or = NkT
n = N/NA or k = R/NA
3
<EK> =
× R/NA × T
2
(c) (i) reaction represents
and
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<EK> = ½m<c >
either build-up of nucleus from light nuclei
or
build-up of heavy nucleus from nuclei
so fusion reaction
(ii) proton and deuterium nucleus will have equal kinetic energies
1.2 × 10–14 = 32 × 8.31 / (6.02 × 1023) × T
T = 5.8 × 108 K
(use of E = 2.4 × 10–14 giving 1.16 × 109 K scores 1 mark)
(iii) either inter-molecular / atomic / nuclear forces exist
or
proton and deuterium nucleus are positively charged / repel
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Page 3
3
Mark Scheme: Teachers’ version
GCE A LEVEL – October/November 2010
Syllabus
9702
(a) (i) 8.0 cm
(ii) 2πf = 220
f = 35
(condone unit)
(iii) line drawn mid-way between AB and CD
(allow ±2 mm)
(iv) v = ωa
= 220 × 4.0
= 880 cm s–1
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(b) (i) 1.
2.
line drawn 2 cm above AB
arrow pointing upwards
(allow ±2 mm)
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(ii) 1.
2.
line drawn 2 cm above AB
arrow pointing downwards
(allow ±2 mm)
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(iii) v = ω√(a2 – x2)
= 220 × √(4.02 – 2.02)
= 760 cm s–1
(incorrect value for x, 0/2 marks)
4
Paper
43
(a) (i) work done moving unit positive charge
from infinity to the point
(ii) charge / potential (difference)
(ratio must be clear)
(b) (i) capacitance = (2.7 × 10–6) / (150 × 103)
(allow any appropriate values)
capacitance = 1.8 × 10–11
(allow 1.8 ±0.05)
(ii) either energy = ½CV 2 or energy = ½QV and Q = CV
energy = ½ × 1.8 × 10–11 × (150 × 103)2 or ½ × 2.7 × 10–6 × 150 × 103
= 0.20 J
(c) either since energy ~ V 2, capacitor has (½)2 of its energy left
or
full formula treatment
energy lost = 0.15 J
© UCLES 2010
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Mark Scheme: Teachers’ version
GCE A LEVEL – October/November 2010
Syllabus
9702
(a) magnetic flux = BA
= 89 × 10–3 × 5.0 × 10–2 × 2.4 × 10–2
= 1.07 × 10–4 Wb
(b) (i) e.m.f. = ∆φ / ∆t
(for ∆φ = 1.07 × 10–4 Wb), ∆t = 2.4 × 10–2 / 1.8 = 1.33 × 10–2 s
e.m.f. = (1.07 × 10–4) / (1.33 × 10–2)
= 8.0 × 10–3 V
7
8
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(c) force on wire = BIL
= 89 × 10–3 × 70 × 10–3 × 6.0 × 10–2
≈ 4 × 10–4 (N)
suitable comment e.g. this force is too / very small (to be felt)
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(a) power / heating depends on I2
so independent of current direction
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(b) either maximum power = I02R or average power = IRMS2R
I0 = √2 × IRMS
maximum power = 2 × average power
ratio = 0.5
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[3]
(a) force due to E-field is equal and opposite to force due to B-field
Eq = Bqv
v = E/B
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(b) either charge and mass are not involved in the equation in (a)
or
FE and FB are both doubled
or
E, B and v do not change
so no deviation
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(a) minimum frequency for electron to be emitted (from surface)
of electromagnetic radiation / light / photons
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(b) E = hc / λ or E = hf and c = fλ
either threshold wavelength = (6.63 × 10–34 × 3.0 × 108) / (5.8 × 10–19)
= 340 nm
or energy of 340 nm photon = 4.4 × 10–19 J
or threshold frequency = 8.7 × 1014 Hz
or 450 nm → 6.7 × 1014 Hz
appropriate comment comparing wavelengths / energies / frequencires
so no effect on photo-electric current
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(ii) current = 8.0 × 10–3 / 0.12
≈ 70 mA
6
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Page 5
Mark Scheme: Teachers’ version
GCE A LEVEL – October/November 2010
Syllabus
9702
Paper
43
Section B
9
(a) (i) edges can be (clearly) distinguished
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(ii) e.g. size of X-ray source / anode / target / aperture
scattering of X-ray beam
pixel size
(any two, 1 each)
further detail e.g. use of lead grid
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[3]
(b) X-ray image involves a single exposure
CT scan: exposure of a slice from many different angles
repeated for different slices
CT scan involves a (much) greater exposure
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10 (a) e.g. infinite input impedance / resistance
zero output impedance / resistance
infinite gain
infinite bandwidth
infinite slew rate
(any three, 1 each)
(b) (i) with switch open, V – is less (positive) than V +
output is negative
with switch closed, V – is more (positive) than V + so output is positive
(allow similar scheme if V – more positive than V + treated first)
(ii) 1.
2.
diodes connected correctly between output and earth
green identified correctly
(do not allow this mark if not argued in (i))
11 (a) (i) I / I0 = exp(–1.5 × 2.9)
= 0.013
(ii) I / I0 = exp(–4.6 × 0.95)
= 0.013
(b) attenuation (coefficients) in muscle and in fat are similar
attenuation (coefficients) in bone and muscle / fat are different
contrast depends on difference in attenuation
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Page 6
12 (a) (i) 1.
2.
Mark Scheme: Teachers’ version
GCE A LEVEL – October/November 2010
Syllabus
9702
signal has same variation (with time) as the data
consists of (a series of) ‘highs’ and ‘lows’
either analogue is continuously variable (between limits)
or
digital has no intermediate values
(ii) e.g. can be regenerated / noise can be eliminated
extra data can be added to check / correct transmitted signal
(any two reasonable suggestions, 1 each)
(b) (i) analogue signal is sampled at (regular time) intervals
sampled signal is converted into a binary number
(ii) one channel is required for each bit (of the digital number)
© UCLES 2010
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Paper
43
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