9702 w06 ms_all

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS

GCE Advanced Subsidiary Level and GCE Advanced Level

MARK SCHEME for the October/November 2006 question paper

9702 PHYSICS

9702/01 Paper 1 (Multiple Choice), maximum raw mark 40

This mark scheme is published as an aid to teachers and students, 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.

All Examiners are instructed that alternative correct answers and unexpected approaches in candidates’ scripts must be given marks that fairly reflect the relevant knowledge and skills demonstrated.

Mark schemes must be read in conjunction with the question papers and the report on the examination. The grade thresholds for various grades are published in the report on the examination for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses.

• CIE will not enter into discussions or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the October/November 2006 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses.

Page 2 Mark Scheme Syllabus Paper

GCE A/AS LEVEL - OCT/NOV 2006 9702 01

© UCLES 2006

Question Number

Key Question Number

Key

1 D 21 D

2 B 22 B

3 A 23 C

4 D 24 B

5 A 25 C

6 D 26 D

7 C 27 C

8 D 28 A

9 C 29 B

10 B 30 C

11 D 31 A

12 B 32 D

13 B 33 A

14 B 34 A

15 C 35 D

16 D 36 B

17 A 37 B

18 C 38 C

19 C 39 D

20 B 40 B


GCE Advanced Subsidiary Level and GCE Advanced Level MARK SCHEME for the October/November 2006 question paper

9702 PHYSICS

9702/02 Paper 2 (Structured), maximum raw mark 60







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1 (a) (i) product of force and distance moved M1 (by force) in the direction of the force A1 [2] (ii) work (done) per unit time (idea of ratio needed) B1 [1]

(b) either work/time or power = (force × distance)/time M1

to give power = force × velocity A1 [2]

(c) (i) kinetic energy (= ½mv2) = ½ × 1900 × 272 C1

power = 692550 / 8.1 = 8.55 × 104 W A1 [2] (ii) either for equal increments of speed, increments of EK are different M1 so longer time (to increase speed) at high speeds A1 [2] or air resistance increases with speed (M1) so driving force (and acceleration) reduced (A1) or P (= Fv) = mav (M1) (P and m constant) so when v increases, a decreases (A1) 2 (a) uses a tangent (anywhere), not a single point C1 draws tangent at correct position B1

acceleration = 1.7 ± 0.1 A2 [4]

(outside 1.6 → 1.8 but within 1.5 → 1.9, allow 1 mark) (b) (i) because slope (of tangent of graph) is decreasing M1 acceleration is decreasing A1 [2] (ii) e.g. air resistance increases (with speed) (angle of) slope of ramp decreases B1 [1] (c) (i) scatter of points about line B1 [1] (ii) intercept / line does not go through origin B1 [1] 3 (a) helium nucleus OR contains two protons and two neutrons B1 [1] (b) kinetic energy = ½mv2 C1

½ × 4 × 1.66 × 10-27 × v2 = 1.07 × 10-12 A1

v = 1.8 × 107 m s-1 A0 [2] (c) (i) sum of momenta (in any direction) is constant / total momemtum is constant M1 in a closed system / no external force A1 [2]

(ii) momentum of francium (= 0) = momentum of α + momentum of astatine C1

204 × V = 4 × 1.8 × 107 C1

V = 3.5 × 105 m s-1 A1 [3] (nuclei incorrectly identified, 0/3 nuclei correctly identified but incorrect masses, -1 each error) (d) another particle / photon is emitted M1

at an angle to the direction of the α-particle A1 [2] (allow 1 mark for ‘Francium nucleus is not stationary’)



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4 (a) (i) when two (or more) waves meet (at a point) M1 there is a change in overall intensity / displacement A1 (ii) constant phase difference (between waves) B1 [3]

(b) (i) dsinθ = nλ B1

(10-3 / 550) sin90 = n × 644 × 10-9 C1 n = 2.8 C1 so two orders A1 [4] (power-of-ten error giving 2800 orders, allow 1/3 only for calculation of n)

(ii) 1. dsinθ = nλ (either here or in (i) – not both)

θ is greater so λ is greater B1 [1]

2. when n is larger, ∆θ is larger M1 so greater in second order A1 [2] 5 (a) metal: crystalline / lattice / atoms in regular pattern B1 (atoms in regular) pattern that repeats itself (within crystal) B1 [2] polymer: long chains of atoms / molecules B1 chain consists of ‘units’ that repeat themselves B1 [2] (b) (i) e.g. latex is soft / not strong / flows / ductile B1 elastic limit easily exceeded B1 [2] (allow any two sensible comments, 1 each) (ii) more solid / does not flow / stronger / higher ultimate tensile stress more brittle elastic limit much higher increased toughness (any two, 1 each) B2 [2]

6 (a) (i) R = ρL / A B1

(ii) strain = ∆L / L B1

either ∆R = ρ∆L /A or R ∝ L with ρ and A constant B1

dividing, ∆R / R = ∆L / L A0 [3] (b) Young modulus = stress / strain C1

strain = 72.0 / (1.20 × 10-7 × 2.10 × 1011) C1

= 2.86 × 10-3 (allow 1/350 A1

∆R = 2.86 × 10-3 × 4.17 = 1.19 × 10-2 Ω A1 answer given to 3 sig. fig B1 [5] 7 (a) both measure (energy / work) / charge B1 for e.m.f., transfer of chemical energy to electrical energy B1 for p.d., transfer of electrical energy to thermal energy / other forms B1 [3] (b) (i) I1 + I2 = I3 B1 [1] (ii) 1. E2 = I2R2 + I3R3 B1 [1] 2. E1 - E2 = I1R1 - I2R2 B1 [1]




9702 PHYSICS

9702/03 Paper 3 (Practical 1), maximum raw mark 25







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Part (b) (ii) First value for d in range 0 to 1.0 m and correct working for T 1 (i.e. mass in kg x 9.8. Expect to see 1.47 N. Ignore sf.) Part (c) Percentage uncertainty in d (must show working) 2

∆d = 1 mm to 5 mm (1 mark) Ratio correct and x 100 (1 mark) Part (d) (i) Readings 6 6 sets of readings in the table scores 6 marks; 5 sets then 5 marks etc. Don’t allow a set of readings where suspended mass is 0. Check a value for √T. Tick if correct. If incorrect, write in correct value and – 1. Minor help from Supervisor then – 1. Major help then – 2. Repeated readings 1 For each value of T there must be at least two values of d. Do not award this mark if all the length readings are identical for every T value. Quality of results 1 At least five points must be plotted to qualify for this mark. Judge by scatter of points about the line of best fit (all d values within ± 0.03 m of marker’s best line). Do not award this mark if the wrong graph has been plotted (i.e. the quality cannot be judged), or if there is a negative or curved trend. Do not award this mark if range of d is less than 0.20 m. Column headings 1 Apply to √T only. Expect to see √T /N1/2 or √T (N1/2) or √(T/N) etc. Consistency 1 Apply to raw values of d only. Check values by row; decimal places must be the same in every row. Part (d) (ii) Justification of sf in √T 2 Must be same as or one better than (1 mark) the sf in T or M (1 mark). ‘Raw values’ ideas get one out of two marks only. Ignore references to sf in g. Reference to decimal places scores zero.



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Part (e) (i) Axes 1 Scales must be such that the plotted points occupy at least half the graph grid in both the x and y directions. Scales must be labelled with the quantity plotted. Ignore units. Do not allow awkward scales (e.g. 3:10, 6:10 etc). Allow reversed axes. Plotting of points 1 All points must be plotted. Check a suspect plot. Circle and tick if correct. If incorrect, show correct position with arrow, and -1. Work to half a small square. Line of best fit 1 There must be at least 5 trend points. There must be a reasonable balance of points about the line of best fit. Part (e) (ii) Determination of gradient 1

∆ used must be greater than half the length of the drawn line; read-offs must be correct to half a small square. Part (f) Gradient equated with 1/2f√m 1 Correct method of working to give value of m, i.e. substitution of gradient value, not substitution of a point 1 Value of m in range 0.40 g m-1 to 0.60 g m-1 (or ± 0.10 g m-1 of SV) 1 Unit of m correct (e.g. g m-1). Independent mark. 1 Part (g) Difficulty (must be non-trivial, with sufficient detail). 1 e.g. difficult to measure d (accurately) e.g. wire difficult to see e.g. hard to tell when amplitude is maximum e.g. difficult to hold plug/rule still e.g. parallax error Improvement (detail may be clear from the ‘difficulty’). 1 e.g. mount ruler in stand e.g. mount plug in stand e.g. put coloured card behind wire 25 marks in total.




9702 PHYSICS

9702/04 Paper 4 (Core), maximum raw mark 60







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1 (a) either ratio of work done to mass/charge

or work done moving unit mass/charge from infinity or both have zero potential at infinity B1 [1]

(b) gravitational forces are (always attractive) B1 electric forces can be attractive or repulsive B1 for gravitational, work got out as masses come together

/mass moves from infinity B1 for electric, work done on charges if same sign, work got out if opposite sign as charges

come together B1 [4]

2 (a) (i) idea of heat lost (by oil) = heat gained (by thermometer) C1 32 x 1.4 x (54 – t) = 12 x 0.18 x (t – 19) C1 t = 52.4°C A1 [3] (ii) either ratio (= 1.6/54) = 0.030 or (=1.6/327) = 0.0049 A1 [1]

(b) thermistor thermometer (allow ‘resistance thermometer’) B1 because small mass/thermal capacity B1 [2]

(c) boiling point temperature is constant M1 further comment

e.g. heating of bulb would affect only rate of boiling A1 [2]

3 (a) use of a = –ω2x clear C1

either ω = √(2k/m) or ω2 = (2k/m) B1

ω = 2 πf C1 f = (1/2 π)√(2 x 300)/0.240) B1 = 7.96 ≈ 8 Hz A0 [4]

(b) (i) resonance B1 [1]

(ii) 8 Hz B1 [1]

(c) (increase amount of) damping B1 without altering (k or) m …(some indirect reference is acceptable) B1 sensible suggestion B1 [3]

4 (a) (i) GMm (R + h1)–1

– (R + h2)–1

B1 ½m v1

2 – v2

2 B1 [2]

(b) 2M x 6.67 x 10–11

(26.28 x 106)–1

– (29.08 x 106)–1

= 53702 – 5090

2 B1

M x 4.888 x 10–19

= 2.929 x 106 C1

M = 6.00 x 1024

kg A1 [3] (If equation in (a) is dimensionally unsound, then 0/3 marks in (b), if dimensionally sound but

incorrect, treat as e.c.f.)

5 (a) (i) (induced) e.m.f proportional/equal to rate of change of flux (linkage) B1 (allow ‘induced voltage, induced p.d.) flux is cust as the disc moves M1 hence inducing an e.m.f A0 [2]

(ii) field in disc is not uniform/rate of cutting not same/speed of disc not same (over whole disc) B1

so different e.m.f.’s in different parts of disc M1 lead to eddy currents A0 [2]

(b) eddy currents dissipate thermal energy in disc B1 energy derived from oscillation of disc B1 energy of disc depends on amplitude of oscillations B1 [3]



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6 (a) (i) peak voltage = 6√2 C1 peak voltage = 8.48 V A1 [2] (ii) zero because either no current in circuit (and V = IR) or all p.d. across diode B1 [1] (b) waveform: half-wave rectification B1 peak height at about 4.25 cm B1 half-period spacing of 2.0 cm B1 [3] (allow ±¼ square for height and half-period) (c) (i) capacitor shown in parallel with resistor B1 [1] (ii) either energy = ½CV

2 or = ½QV and Q = CV C1

= ½ x 180 x 10–6

x (6√2)2 C1

= 6.48 x 10–3

J A1 [3] (iii) either fraction = 0.43

2 or final energy = 1.2 mJ C1

fraction = 0.18 A1 [2] 7 (a) (i) quantum/packet/discrete amount of energy M1 electromagnetic mentioned A1 [2] (ii) max. k.e. corresponds to electron emitted from surface B1 energy is required to bring electron to surface B1 [2] (b) at higher frequency, fewer photons (per second) for same intensity M1 so rate of emission decreases A1 [2] (allow argument based on photoelectric efficiency) 8 (a) (i) either number = 6.02 x 10

23 x (2.65 x 10

–6/234)

or number = (2.65 x 10–9

)/(234 x 1.66 x 10–27

) C1 = 6.82 x 10

15 A1 [2]

(ii) A = λ N C1 604 = λ x 6.82 x 10

15

λ = 8.86 x 10–14

s–1

A1 [2] (iii) T½ = ln2/λ = 7.82 x 10

12 s C1

= 2.48 x 105 years A1 [2]

(b) half-life is (very) long (compared with time of counting) B1 [1] (c) there would be appreciable decay of source during the taking of measurements B1 [1]




9702 PHYSICS

9702/05 Paper 5 (Practical), maximum raw mark 30







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Question 1

(b) (iii) Resistance of LDR calculated correctly and greater than 1 kΩ and less than 100 kΩ. 1 (b) (iv) Justification of sf in R (in text or value in (iii)). Relate to V and I. Do not allow just one 1 unless valid reason given. Do not allow ‘raw’ data. Ignore dp if SF correct.

(c) Readings. Wrong trend in I (or R) −1. 2 6 sets scores two marks. 5 sets one mark. Allow more than 6 sets without penalty.

Minor help from the Supervisor, −1. Major help, then −2. If help has been given then write SR at the top of the front page of the script, and give a brief explanation of the type of help that has been given by the table of results. (c) lg R and lg N correct; one mark each. Values must be checked. 2 (c) Column headings consistent. Ignore POT. 1

V, I, R and lgR column heading must contain a quantity and any valid unit. e.g. lg(R/Ω). (c) Consistency of raw readings. I and V only. 1 (d) (i) Axes inverted or wrong graph loses this mark. 1 The axes must be labelled with the quantities plotted. (ignore units) The plotted points must occupy at least half the graph grid in both the x and y directions (i.e. 4 large squares in the x-direction and 6 large squares in the y-direction). Do not allow more than 3 large squares between the labels on an axis. Do not allow awkward scales (e.g. 3:10, 6:10 etc.). (d) (i) Plotting of points 1 All the observations must be plotted. Count the number of plots and ring this total on the grid. Do not allow plots in the margin area. Check one suspect plot. Circle this plot. Tick if correct. If incorrect, mark the correct position with a small cross and use an arrow to indicate where the plot should have been,

and −1. Allow errors up to and including half a small square. (d) (ii) Line of best fit. Too much scatter loses this mark. 1 A linear trend is expected for this mark. At least 5 or more trend plots on the grid. There must be a reasonable balance of points about the drawn line. (d) (iii) Gradient. Expect negative gradient. Allow ecf. 1 Ignore any units given with the value.

Hypotenuse of ∆ must be ≥ half the length of line drawn.

Check the read-offs. Work to half a small square. ∆x/∆y gets zero. Values taken from the table that lie on the line to within half a small square are acceptable. (d) (iii) y-intercept Accept substitution into y = mx + c using a point on the line. 1 (e) a = 10y-intercept 1 Check value from candidate’s y-intercept. Allow ecf. from graph (e) b = gradient. Allow ecf from graph. 1



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(f) (i) Value of diameter of pin. Check value between 0.60 – 0.70 mm. Must have 2dp. 1

(If out of range check Supervisor’s value ± 0.05 mm) (f) (ii) Check substitution for area of check value if no substitution. Ignore POT. 1 Expect A = 0.33 mm2. allow ecf from (f) (i). (f) (iii) Repeat readings of diameter (and check area). 1

(g) Value of R in range 200 – 2000 Ω. 1 (g) 2/3 S.F. only. 1

20 marks in total.



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Question 2 A1 (Measure) p.d. and find a force (could be in a table or graph). Change p.d. and repeat. 1 i.e. correct procedure. Do not give for only identifying the variables. This mark can be scored if the method is unworkable. A2 Measurement of p.d. – voltmeter connected in parallel with capacitor or power supply on 1 diagram or voltage read from power supply in text. Wrong diag loses this mark. A3 Workable electrical arrangement: d.c. power supply on diag or in text. 1 Ignore Voltmeter in series. Ammeter in parallel loses this mark. Do not allow discharge of circuit while measuring force. If diagram wrong this loses this mark. A4 Method of changing the p.d. (diag or text). 1 Variable power supply or potential divider circuit. Do no allow variable resistor in series. Do not allow changing distance. B1 Measure the force/(mass) with tpb or force with newtonmeter. 1 Or measure force from a mass/lever/pulley system. B2 Workable mechanical arrangement to measure force on diag. 1 Allow workable loading/lever/pulley system. B3 Plates close together/large surface area or HT/EHT/hight voltage to 1 make force large/measurable. C Any one safety precaution with reason. 1 e.g. wear insulating/rubber gloves: earth/insulate one plate wrt top pan balance or newtonmeter; discharge before touching plates to avoid/prevent shock/short circuit. Do not allow not touching plates (precaution needed). D1/2 Any further good design features. 2 Some of these might be: Two fixed points shown on the diagram (appropriate clamps or supports). Distance between the plates should be kept constant. Method of achieving constant separation of plates (spacers or measurement; no insulators or dielectrics)/adjust newtonmeter position to give same separation. Force = mg Force is the change in readings. Calibrate springs to give force reading. Approx. p.d (greater than 100 V)/distance (less than 1 cm)/Area (greater than 400 cm2)

10 marks in total.




9702 PHYSICS

9702/06 Paper 6 (Options), maximum raw mark 40







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Option A – Astrophysics and Cosmology 1 (a) gaseous/rocky/icy/approx. spherical object B1 that orbits the Sun / a star B1 [2] (b) Venus must have passed between Sun and Earth B1 1 AU is (mean) distance between Earth and Sun B1 [2] 2 (a) (light of a particular wavelength as observed) when source is moving away (from observer) M1 has a longer wavelength A1 than when source is stationary (with respect to observer) B1 [3] (b) (extent of) redshift depends on v/c B1 can only be observed when v is significant when compared to c B1 [2] 3 (a) v is speed of separation of (any two) galaxies B1 d is the separation of the galaxies B1 [2] (max 1 mark if refers to Earth)

(b) 1 Mpc = 3.09 × 1019 km (allow 3.0 → 3.2) C1 age = 1 / H0 C1

age = (3.09 × 1019) / 60

= 5.2 × 1017 s A1 [3] 4 (a) e.g. dark matter does not emit light dark matter does not reflect light (any two sensible suggestions, 1 each) B2 [2] (b) e.g. estimate of mass unreliable M1 because there are neutrinos A1 e.g. do not know extent of Universe M1 due to redshift / intensity of light A1 [4] (any sensible suggestion (M1) with reason (A1))



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Option F – The Physics of Fluids 5 (a) symmetrical pattern ‘above’ and ‘below’ B1 lines closest together at widest part of object B1 smooth lines tending towards initial separation B1 [3] (b) either separation of lines is not constant or path lengths differ B1 [1] 6 (a) centre of buoyancy is above the centre of mass B1 (if displaced sideways) weight and upthrust provide couple to keep tube upright B1 [2] (do not allow argument in terms of metacentre)

(b) either force on base = Lρg × A or weight of liquid displaced = ρLAg M1 this equals weight Mg this equals weight Mg A1

hence L = M/Aρ hence L = M/Aρ A0 [2]

(c) M/A = Lρ = constant C1

new length = 12.1 × (0.99/1.11) = 10.8 cm C1 change in length = 1.3 cm A1 [3] 7 (a) (apparent) weight acts downwards B1 drag force acts upwards B1

resultant force = weight - kv OR drag ∝ v B1 as speed increases, resultant force / acceleration becomes less B1 (so) speed increases to a constant value B1 [5] (b) fluid is dragged along by the surface of the (spinning) sphere B1 on one ‘side’ speed of fluid is greater than on other M1 this difference in speed creates a pressure difference / difference in drag /

turbulence A1 so sphere moves sideways (in direction of lower pressure) A1 [4]



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Option M – Medical Physics 8 (a) pulse of ultrasound B1 reflected at boundary (between any two media) B1 reflected pulse detected by (piezo-electric) crystal B1 signal from crystal amplified / processed and displayed B1 [4] (b) crystals are at different orientations B1 signals from all crystals are combined B1 to build up a (2D) image B1 [3] 9 (a) (i) process by which objects at different distances from the eye M1 are brought to a focus (on the retina) A1 [2] (ii) ciliary muscles alter shape of lens B1 this alters the power/focal length of the lens B1 [2] (b) pupil varies in diameter C1 power (intensity) admitted is proportional to diameter2 B1 either variation of diameter is small / small factor or variation of light intensity is large / (very) large factor B1 [3] 10 (a) IL = 10 lg(I/I0)

= 10 lg(1.6 × 10-10 / 1 × 10-12) C1 = 22 dB A1 range is from 100 Hz B1 to 10 kHz B1 [4] (b) e.g. threshold intensity rises upper frequency (limit) decreases lower frequency (limit) rises (any two suggestions, 1 each, max 2) B2 [2] (allow 1 mark for ‘line closes up’ / smaller frequency range)



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Option P – Environmental Physics 11 (a) (i) slows down neutrons M1 to enable further fission reactions A1 [2] (ii) absorbs neutrons M1 to control rate of reaction / power A1 [2] (iii) acts as a biological shield B1 maintains coolant around the core / containment vessel B1 [2] (b) kinetic energy of fission fragments B1 causes heating of the core / fuel rods B1 this thermal energy is carried away by the coolant B1 [3] (c) e.g. either minimal / no release of CO2 into the atmosphere or minimal / no release of gases causing global warming no huge storage areas required at the power station maintenance possible whilst on full load (any two suggestions, 1 each, max 2) B2 [2]

12 (a) incident power = 960 × 2.5 × 10-4 = 0.24 W C1

efficiency = (30 × 10-3) / 0.24 = 0.13 A1 [2] (b) (i) large (surface) area required B1 (ii) connect many cells in series for higher voltage B1 connect many cells in parallel for larger current B1 [3] 13 (a) 30% delivered to motor C1

cost = 5.4 × (100/30) × 5 = 90 cents A1 [2] (allow 1 mark for answer 100 cents) (b) (for both,) there is a need to heat water / for heat energy B1 this energy provided from ‘production losses’ (so reducing overall costs) B1 [2]



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Option T – Telecommunications 14 (a) satellite with orbit having period 24 hours B1 orbits above the Equator B1 from west to east / orbits in same sense B1 [3] (b) loss = 10 lg(P2 / P1) C1 -170 = 10 lg(P2 / 2400) C1

P2 = 2.4 × 10-14 W A1 [3] (c) amplified otherwise power too low to be picked up on Earth B1 either frequency changed to prevent swamping / interference of signal

received (from Earth) or prevent feedback B1 [2] 15 (a) variations in either amplitude or frequency of a wave B1 either in synchrony with displacement of information signal or in order to carry information on the wave B1 [2] (b) (i) 9 kHz B1 [1]

(ii) LW frequency range is 30 kHz → 300 kHz C1 number = 270 / 9 C1 = 30 A1 [3] (c) sketch: carrier frequency as vertical line and two sidebands M1 reasonable symmetry A1 sideband indicating approx. 4500 Hz range B1 [3] (if sidebands shown as vertical lines, allow max. 1 mark) 16 (a) e.g. link between house and exchange for a telephone (any one suggestion, 1 mark) B1 [1] (b) e.g. greater bandwidth less noise less attenuation (any two suggestions, 1 each, max 2) B2 [2]

Education

9702 w06 ms_all