• 9702 June 2012 Paper 12 Worked Solutions | A-Level Physics

Paper 12

1 C                  11 B                21 C                31 C

2 D                  12 D                22 C                32 C

3 D                  13 A                23 C                33 D

4 B                  14 B                24 B                34 B

5 B                  15 D                25 C                35 D

6 A                  16 D                26 D                36 D

7 A                  17 B                27 C                37 D

8 D                  18 D                28 D                38 C

9 A                  19 B                29 C                39 B

10 A                20 D                30 B                40 B

Notes for some specific questions:

3 - Ans: D. {Detailed explanations for this question is available as Solution 1117 at Physics 9702 Doubts | Help Page 240 - http://physics-ref.blogspot.com/2016/07/physics-9702-doubts-help-page-240.html}

4 – Ans: B. {Detailed explanations for this question is available as Solution 287 at Physics 9702 Doubts | Help Page 48 - http://physics-ref.blogspot.com/2015/01/physics-9702-doubts-help-page-48.html}

5 – Ans: B.

A mass is dropped from rest, and falls through a distance of 2.0 m in a vacuum. An observer records the time taken for the mass to fall through this distance using a manually operated stopwatch and repeats the measurements a further two times.


6 - Ans: A.
The diagram shows two complete pulses on the screen of a cathode-ray oscilloscope. A grid of 1 cm squares covers the screen.


7 - Ans: A. {Detailed explanations for this question is available as Solution 518 at Physics 9702 Doubts | Help Page 101 - http://physics-ref.blogspot.com/2015/04/physics-9702-doubts-help-page-101.html}

8 – Ans: D.

Two markers M1 and M2 are set up a vertical distance h apart. A steel ball is released at time zero from a point a distance x above M1.

9 – Ans: A. Brick is falling, so height decreases with time. [C and D are incorrect] Gradient of the graph gives speed of fall of brick. Due to gravity, there is an acceleration of 9.81ms^-2, so speed keeps on increasing until it reaches the ground. So, gradient is not constant. [B is incorrect]

10 - Ans: A. {Detailed explanations for this question is available as Solution 947 at Physics 9702 Doubts | Help Page 195 - http://physics-ref.blogspot.com/2015/09/physics-9702-doubts-help-page-195.html}


11 - Ans: B. {Detailed explanations for this question is available as Solution 513 at Physics 9702 Doubts | Help Page 100 - http://physics-ref.blogspot.com/2015/03/physics-9702-doubts-help-page-100.html}

12 - Ans: D. {Detailed explanations for this question is available as Solution 932 at Physics 9702 Doubts | Help Page 192 - http://physics-ref.blogspot.com/2015/08/physics-9702-doubts-help-page-192.html}

13 – Ans: A. {Detailed explanations for this question is available as Solution 425 at Physics 9702 Doubts | Help Page 80 - http://physics-ref.blogspot.com/2015/03/physics-9702-doubts-help-page-80.html}

14 – Ans: B. {Detailed explanations for this question is available as Solution 974 at Physics 9702 Doubts | Help Page 201 - http://physics-ref.blogspot.com/2015/09/physics-9702-doubts-help-page-201.html}

15 – Ans: D. {Detailed explanations for this question is available as Solution 769 at Physics 9702 Doubts | Help Page 155 - http://physics-ref.blogspot.com/2015/05/physics-9702-doubts-help-page-155.html}


16 - Ans: D. {Detailed explanations for this question is available as Solution 813 at Physics 9702 Doubts | Help Page 163 - http://physics-ref.blogspot.com/2015/06/physics-9702-doubts-help-page-163.html}


17 - Ans: B. {Detailed explanations for this question is available as Solution 557 at Physics 9702 Doubts | Help Page 109 - http://physics-ref.blogspot.com/2015/04/physics-9702-doubts-help-page-109.html}


20 - Ans: D. {Detailed explanations for this question is available as Solution 1062 at Physics 9702 Doubts | Help Page 223 - http://physics-ref.blogspot.com/2015/11/physics-9702-doubts-help-page-223.html}



22 - Ans: C. {Detailed explanations for this question is available as Solution 332 at Physics 9702 Doubts | Help Page 58 - http://physics-ref.blogspot.com/2015/02/physics-9702-doubts-help-page-58.html}

23 - Ans: C. {Detailed explanations for this question is available as Solution 361 at Physics 9702 Doubts | Help Page 64 - http://physics-ref.blogspot.com/2015/02/physics-9702-doubts-help-page-64.html}


24 - Ans: B. {Detailed explanations for this question is available as Solution 476 at Physics 9702 Doubts | Help Page 92 - http://physics-ref.blogspot.com/2015/03/physics-9702-doubts-help-page-92.html}


25 - Ans: C. {Detailed explanations for this question is available as Solution 363 at Physics 9702 Doubts | Help Page 65 - http://physics-ref.blogspot.com/2015/02/physics-9702-doubts-help-page-65.html}

26 – Ans: D. Should allow for reflection. Total distance = 2(150) = 300m. Speed = 3x10⁸ms^-1. So, time = 1x10^-6s = 1μs.

27 - Ans: C. {Detailed explanations for this question is available as Solution 640 at Physics 9702 Doubts | Help Page 127 - http://physics-ref.blogspot.com/2015/04/physics-9702-doubts-help-page-127.html}



28 - Ans: D. {Detailed explanations for this question is available as Solution 166 at Physics 9702 Doubts | Help Page 28 - http://physics-ref.blogspot.com/2014/11/physics-9702-doubts-help-page-28.html}


29 - Ans: C. {Detailed explanations for this question is available as Solution 366 at Physics 9702 Doubts | Help Page 66 - http://physics-ref.blogspot.com/2015/02/physics-9702-doubts-help-page-66.html}

30 – Ans: B.

A standing sound wave is set up between a loudspeaker and a wall.
 

31 - Ans: C. {Detailed explanations for this question is available as Solution 678 at Physics 9702 Doubts | Help Page 137 - http://physics-ref.blogspot.com/2015/05/physics-9702-doubts-help-page-137.html}


32 - Ans: C. {Detailed explanations for this question is available as Solution 1114 at Physics 9702 Doubts | Help Page 239 - http://physics-ref.blogspot.com/2016/06/physics-9702-doubts-help-page-239.html}

33 – Ans: D. R=ρL/A.  A is incorrect since the charged particles (ions and electrons) are already present in the wire. B is incorrect because the wire with the smaller diameter, and hence, smaller cross-sectional area resulting in a higher resistance. So, for same current to flow in both of them [I=V/R], a larger potential difference should be applied to the smaller wire, causing the average velocity of the charged particles to be faster in the smaller wire. C incorrect because larger diameter > smaller resistance > smaller pd required > less energy provided to charged particles.

35 - Ans: D. {Detailed explanations for this question is available as Solution 364 at Physics 9702 Doubts | Help Page 65 - http://physics-ref.blogspot.com/2015/02/physics-9702-doubts-help-page-65.html}


36 - Ans: D. {Detailed explanations for this question is available as Solution 426 at Physics 9702 Doubts | Help Page 81 - http://physics-ref.blogspot.com/2015/03/physics-9702-doubts-help-page-81.html}

37 – Ans: D.{Detailed explanations for this question is available as Solution 789 at Physics 9702 Doubts | Help Page 159 - http://physics-ref.blogspot.com/2015/06/physics-9702-doubts-help-page-159.html}

38 - Ans: C. {Detailed explanations for this question is available as Solution 182 at Physics 9702 Doubts | Help Page 29 - http://physics-ref.blogspot.com/2014/11/physics-9702-doubts-help-page-29.html}

40 - Ans: B.
Radon 22286Rn is the start of a decay chain that forms bismuth 21483Bi by alpha and beta emission. For the decay of each nucleus of radon, how many α−particles and β−particles are emitted?

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.