Physics (AS & A Level) Paper 42

gravitational force provides/is the centripetal force same gravitational force (by Newton III) [2]

ω = 2π / T = 2π / (4.0 × 365 × 24 × 3600) = 5.0 (4.98) × 10–8 rad s–1 [2]

(centripetal force =) MAdω2 = MB(2.8 × 108 –d)ω2 or MAdA = MBdB MA / MB = 3.0 = (2.8 × 108 – d) / d d = 7.0 × 107 km [3]

GMAMB / (2.8 × 1011) 2 = MAdω2 MB = (2.8 × 1011) 2 × dω2 / G = (2.8 × 1011) 2 × (7.0 × 1010) × (4.98 × 10–8) 2 / (6.67 × 10–11) = 2.0 × 1029 kg [3]

number of atoms/nuclei in 12 g of carbon-12 [1]

amount of substance containing NA (or 6.02 × 1023) particles/molecules/atoms or which contains the same number of particles/atoms/molecules as there are atoms in 12 g of carbon-12 [2]

pV = nRT 2.0 × 107 × 1.8 × 104 × 10–6 = n × 8.31 × 290, so n = 149 mol or 150 mol [1]

V and T constant and so pressure reduced by 5.0% pressure = 0.95 × 2.0 × 107 or calculation of new n (= 142.5 mol) and correct substitution into pV = nRT (C1) pressure = 1.9 × 107 Pa [2]

loss is 5 / 100 × 150 mol = 7.5 mol or ∆N = 4.52 × 1024 t = (7.5 × 6.02 × 1023) / 1.5 × 1019 or t = 4.52 × 1024 / 1.5 × 1019 = 3.0 × 105 s [3]

no net energy transfer between the bodies or bodies are at the same temperature [1]

thermocouple, platinum/metal resistance thermometer, pyrometer [1]

thermistor, thermocouple [1]

change = 11.5 K [1]

final temperature = 311.2 K [1]

T = 0.60 s and ω = 2π / T ω = 10 (10.47) rad s–1 [2]

energy = ½mω2x0 2 or ½mv2 and v = ωx0 = ½ × 120 × 10–3 × (10.5) 2 × (2.0 × 10–2) 2 = 2.6 × 10–3 J [2]

sketch: smooth curve in correct directions peak at f amplitude never zero and line extends from 0.7f to 1.3f [3]

sketch: peaked line always below a peaked line A peak not as sharp and at (or slightly less than) frequency of peak in line A [2]

lines perpendicular to surface or lines are radial lines appear to come from centre [2]

FE = (1.6 × 10–19) 2 / 4πε0x2 FG = G × (1.67 × 10–27) 2 / x2 FE / FG = (1.6 × 10–19) 2 × (8.99 × 109) / [(1.67×10–27) 2 × (6.67×10–11)] = 1.2 (1.24) × 1036 [3]

FE ≫ FG [1]

e.g. storing energy blocking d.c. in oscillator circuits in tuning circuits in timing circuits any two [2]

1 / 6 + 1 / C + 1 / C = 1 / 4 C = 24 µF [2]

Q = CV = 4.0 × 10–6 × 12 = 48 µC [2]

1. 48 µC 2. 24 µC [2]

number density of charge carriers/free electrons or number per unit volume of charge carriers/free electrons [1]

PX or QY or RZ [1]

VH is inversely proportional to n for semiconductors, n is (much) smaller than for metals [2]

magnetic field would deflect holes and electrons in same direction (because) electrons are (–)ve, holes are (+)ve so VH has opposite polarity/opposite sign [3]

iron rod changes flux (density)/field change of flux in coil Q causes induced e.m.f. [2]

constant reading (either polarity) from time zero to near t1 spike in one direction near t1 clearly showing a larger voltage of opposite polarity zero reading from near t1 to t2 [4]

point P shown at ‘lower end’ of load [1]

Vr.m.s. = 6.0 / √2 = 4.24 V Ir.m.s. = 4.24 / (2.4 × 103) = 1.8 × 10–3 A [2]

capacitor in parallel with load [1]

line from peak to curve at 3.0 V for either half- or full-wave rectified correct curvature on line (gradient becoming more shallow) line drawn as for full-wave rectified [3]

(X–ray) photon produced when electron/charged particle is stopped/accelerated (suddenly) range of accelerations (in target) hence distribution of wavelengths [3]

electron gives all its energy to one photon electron stopped in single collision [2]

de-excitation of (orbital) electrons in target/anode/metal [1]

aluminium sheet/filter/foil (placed in beam from tube) [1]

(long wavelength X-rays) do not pass through the body [1]

(photons of) electromagnetic radiation emitted from nuclei [2]

line of best fit drawn recognises µ as given by the gradient of best-fit line or ln C = ln C0 – µx µ = 0.061 mm–1 (within ±0.004 mm–1, 1 mark;

within ±0.002 mm–1, 2 marks) [4]

aluminium is less absorbing (than lead) or gradient of graph would be less so µ is smaller [2]