9702 November 2012 Paper 12 Worked Solutions | A-Level Physics
Paper 12
1 B 11
A 21 D 31 A
2 A 12
D 22 A 32 B
3 B 13
D 23 A 33 C
4 C 14
D 24 D 34 C
5 B 15
B 25 D 35 C
6 A 16
D 26 D 36 C
7 D 17
C 27 B 37 C
8 A 18
C 28 C 38 B
9 C 19
A 29 A 39 C
10 D 20
D 30 D 40 D
Notes for some specific questions:
2 - Ans: A. {Detailed explanations for this question is available as Solution 746 at Physics 9702 Doubts | Help Page 151 - http://physics-ref.blogspot.com/2015/05/physics-9702-doubts-help-page-151.html}
3 - Ans: B. {Detailed explanations for this question is available as Solution 752 at Physics 9702 Doubts | Help Page 152 - http://physics-ref.blogspot.com/2015/05/physics-9702-doubts-help-page-152.html}
5 – Ans: B. Volume: need to find
cross-sectional area and length. Vernier caliper : least = about 0.05mm, used
to measure comparatively larger object.
6 – Ans: A.
7 - Ans: D. {Detailed explanations for this question is available as Solution 848 at Physics 9702 Doubts | Help Page 169 - http://physics-ref.blogspot.com/2015/06/physics-9702-doubts-help-page-169.html}
8 - Ans: A. {Detailed explanations for this question is available as Solution 758 at Physics 9702 Doubts | Help Page 153 - http://physics-ref.blogspot.com/2015/05/physics-9702-doubts-help-page-153.html}
9 - Ans: C. {Detailed explanations for this question is available as Solution 233 at Physics 9702 Doubts | Help Page 37 - http://physics-ref.blogspot.com/2014/12/physics-9702-doubts-help-page-37.html}
10 – Ans: D. {Detailed explanations for this question is available as Solution 720 at Physics 9702 Doubts | Help Page 145 - http://physics-ref.blogspot.com/2015/05/physics-9702-doubts-help-page-145.html}
11 – Ans:A. 1h = 3600s. Speed in metre per second = 80000
/ 3600 = 22.22ms-1. a = gradient = (22.22 – 0) / (20 – 0) = 1.1ms-2.
(verify units)
12 – Ans: D. change in momentum = mv2
– mv1 = 0.5(8 – (-12)) = 10. Force = Δp/t
= 10 / 0.10 = 100N. (Momentum is a vector and the change in momentum is 10 kgms–1giving
a force of 100 N.)
13 - Ans: D. {Detailed explanations for this question is available as Solution 585 at Physics 9702 Doubts | Help Page 115 - http://physics-ref.blogspot.com/2015/04/physics-9702-doubts-help-page-115.html}
14 - Ans: D. {Detailed explanations for this question is available as Solution 602 at Physics 9702 Doubts | Help Page 119 - http://physics-ref.blogspot.com/2015/04/physics-9702-doubts-help-page-119.html}
16 – Ans: D. There is no viscous
force on a stationary object, so D is correct. For B and C, body sinks.
17 - Ans: C. {Detailed explanations for this question is available as Solution 1047 at Physics 9702 Doubts | Help Page 219 - http://physics-ref.blogspot.com/2015/10/physics-9702-doubts-help-page-219.html}
18 - Ans: C. {Detailed explanations for this question is available as Solution 291 at Physics 9702 Doubts | Help Page 49 - http://physics-ref.blogspot.com/2015/01/physics-9702-doubts-help-page-49.html}
19 – Ans: A. Work done = Force x
distance. Force = Pressure x area = 4000Pa x 500x10-4 m2
= 200N. WD = 200 x 0.3 = 60J (take units into account)
20 - Ans: D. {Detailed explanations for this question is available as Solution 562 at Physics 9702 Doubts | Help Page 110 - http://physics-ref.blogspot.com/2015/04/physics-9702-doubts-help-page-110.html}
21 - Ans: D. {Detailed explanations for this question is available as Solution 831 at Physics 9702 Doubts | Help Page 166 - http://physics-ref.blogspot.com/2015/06/physics-9702-doubts-help-page-166.html}
22 - Ans: A. {Detailed explanations for this question is available as Solution 581 at Physics 9702 Doubts | Help Page 114 - http://physics-ref.blogspot.com/2015/04/physics-9702-doubts-help-page-114.html}
23 – Ans: A. Ice floats on water at
0 °C, so it is less dense than water and its molecules must be on average
further apart than those in water. At a fixed temperature all the molecules, whether
in ice or water, have the same average speed.
26 – Ans: D. {Detailed explanations for this question is available as Solution 794 at Physics 9702 Doubts | Help Page 160 - http://physics-ref.blogspot.com/2015/06/physics-9702-doubts-help-page-160.html}
27 – Ans: B. Young modulus of wire X
is twice that of wire Y. diameter of X is half that of wire Y. Both are
extended with equal strain and obey Hooke’s law. Since strain is equal and
Young modulus of X is twice that of Y, stress on X is twice that on Y. Diameter
of X is half that of Y, so x-area of X is ¼ area of Y.
28 - Ans: C.
The diagram shows two identical loudspeakers driven in phase by a common audio-frequency source.
29 - Ans: A. {Detailed explanations for this question is available as Solution 111 at Physics 9702 Doubts | Help Page 21 - http://physics-ref.blogspot.com/2014/11/physics-9702-doubts-help-page-21.html}
31 – Ans: A. period, T corresponds
to 2cm = 2x0.20μs = 0.4x10-6s.
Frequency, f = 1/T = 2.5x106Hz
= 2.5MHz. Wavelength radio wave: 1m – 100 000km and freq: 300MHz – 3Hz (A
popular incorrect answer was B, but 2.5 MHz is nowhere near the microwave
region (from question, wavelength would be 120 m), (wavelength of microwave:
1mm – 1meter and freq: 300GHz – 300MHz))
33 – Ans: C. Both p and He have same
charge, so deviation occur in the same direction (side). F = Eq. q of He is
twice that of a proton but since its mass is 4 times that of a proton,
deviation is less. E = ½ mv2. v same.
34 – Ans: C. R = ρl/A. R inversely proportional A, so R is less
for larger A. (A incorrect) X and Y are made from same material, so they have
same resistivity (B incorrect). When two wires are connected in series, current
must be the same in both. The extra resistance of X then makes its I2R
term twice that for Y. emf is the same in each loop of a parallel circuit.
(V=IR) For same length of wire, R of X is twice that of Y, so I in X would be
half that in Y for emf to be similar.
36 – Ans: C. {Detailed explanations for this question is available as Solution 968 at Physics 9702 Doubts | Help Page 200 - http://physics-ref.blogspot.com/2015/09/physics-9702-doubts-help-page-200.html}
37 - Ans: C. {Detailed explanations for this question is available as Solution 447 at Physics 9702 Doubts | Help Page 86 - http://physics-ref.blogspot.com/2015/03/physics-9702-doubts-help-page-86.html}
40 - Ans: D.
A different nucleus can be formed by bombarding a stable nucleus with an energetic α-particle.
A different nucleus can be formed by bombarding a stable nucleus with an energetic α-particle.
Explanations have been provided for questions that were found to be more difficult. If you are having other doubts that have not been explained here, you may ask your questions through comments.
