Saturday, August 9, 2014

9702 November 2012 Paper 12 Worked Solutions | A-Level Physics

  • 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. Gradient is –ve and constant. So, C and D incorrect. Systematic error is due to instrument, so all points should lie on line. At x = 0, y should be p, but due to systematic error, this value is reduced. A is correct as it shows no random error but a systematic error with the line not going through p. B shows random error without systematic error.


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.


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}


30 – Ans: D. dsinθ = nλ. d = 1/300 = 3.33x10-3mm = 3.33x10-6m. λ = 690x10-9m. Maximum value for θ = 90o on each side. θ = sin-1(nλ/d).Trial: when n = 4, θ  = 56.0.when n =5, no ans since argument of sin is greater than 1. There are four maxima on each side and one zero-order maximum, so the answer is D.


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}


39 – Ans: C. Nucleon: either a proton or a neutron. With a decay of an alpha particle, 2 neutrons + 2 protons are emitted. So the number of neutrons and protons in the material each diminishes at a rate of 200s-1.






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. 



56 comments:

  1. Could you please explain question 38 too. Really great explanations. Thanks a lot!! :)

    ReplyDelete
    Replies
    1. 38 – Ans: B.
      V=IR. Let resistance of LDR, = R and that of the resistor = 5kΩ. Voltage across (LDR) R = 1.5 x (R / (R+5)). In dark, resistance of LDR is high, so pd across it is high. Resistance of resistor is comparatively negligible, so V = 1.5V. When illuminated, only 1/6 of the 1.5V (=0.25V) occurs across the LDR.

      Delete
  2. Q's 37 please ! I shall be very thankful to you

    ReplyDelete
  3. Can you please explain Q20?

    ReplyDelete
  4. question 14 pleaseeeeee

    ReplyDelete
  5. Replies
    1. Solution for Q13 has been included

      Delete
  6. Can you explain q14 ��

    ReplyDelete
  7. Can you please explain question 4 of november 2012 variant 21, the one about the waves :S thankyou

    ReplyDelete
    Replies
    1. It's explained as solution 689 at
      http://physics-ref.blogspot.com/2015/05/physics-9702-doubts-help-page-139.html

      Delete
  8. can u please explain November 2012 paper 13 Q28?

    ReplyDelete
    Replies
    1. Check solution 734 at
      http://physics-ref.blogspot.com/2015/05/physics-9702-doubts-help-page-149.html

      Delete
  9. q3 plzzzzzzzzzzzzz

    ReplyDelete
  10. can you explain q13 of oct 2012 variant 11 please ?

    ReplyDelete
    Replies
    1. See solution 66 at
      http://physics-ref.blogspot.com/2014/11/physics-9702-doubts-help-page-12.html

      Delete
  11. please explain q29 and q15 of oct 2012 (11) aswell thanks :)

    ReplyDelete
    Replies
    1. For Q15, see solution 775 at
      http://physics-ref.blogspot.com/2015/05/physics-9702-doubts-help-page-156.html

      For Q29, see solution 526 at
      http://physics-ref.blogspot.com/2015/04/physics-9702-doubts-help-page-102.html

      Delete
  12. in q26, why can't option C be correct i.e both materials are plastic ?
    secondly doesn't the second material (the one with the curve) break at a lesser force than the first material (the one that is almost linear) ?

    ReplyDelete
  13. explanation for answers in nov 2012 variant 13 pls

    ReplyDelete
    Replies
    1. A page for the whole paper has not been added yet. But you can ask for the specific questions in that paper in the meantime.

      Delete
  14. questions 5 7 9 10 11 12 14 15 17 18 19 21 22 24 25 32 36 37 nov 2012 variant 13 pls

    ReplyDelete
    Replies
    1. For Q9, see 278 at
      http://physics-ref.blogspot.com/2015/01/physics-9702-doubts-help-page-46.html

      For Q18, see 101 at
      http://physics-ref.blogspot.com/2014/11/physics-9702-doubts-help-page-19.html

      Delete
  15. can you please explain q7

    ReplyDelete
  16. Oct 2012/13 Q 3,13,21,25,26,33,35 Thank You!

    ReplyDelete
    Replies
    1. For Q25, see solution 824 at
      http://physics-ref.blogspot.com/2015/06/physics-9702-doubts-help-page-164.html

      For Q33, see solution 830 at
      http://physics-ref.blogspot.com/2015/06/physics-9702-doubts-help-page-166.html

      For Q35, see solution 92 at
      http://physics-ref.blogspot.com/2014/11/physics-9702-doubts-help-page-17.html

      Delete
  17. Oct/Nov 2012/13 Q21 thank you...

    ReplyDelete
    Replies
    1. Check solution 977 at
      http://physics-ref.blogspot.com/2015/09/physics-9702-doubts-help-page-202.html

      Delete
  18. Excuse me.. may I have the link for Oct/Nov 2012/13 worked solutions?
    Thanks

    ReplyDelete
    Replies
    1. The complete paper has not been solved yet, but some of the questions may be available. Let me know which questions you are having difficulties.

      Delete
    2. Question 17 please :) I found the others on ur website, thanks a lot!
      btw we are supposed to draw the triangle and see which one is a continuous arrow for equilibrium right? I tried and I saw C is not continuous.

      Delete
  19. Hello...How do I find the questions for the papers you have not put up for multi choice??? Your help and efforts are highly appreciated

    ReplyDelete
  20. Can you plz upload the other multichoice variants.....plzzzzzzz.....i really admire your help :D

    ReplyDelete
    Replies
    1. GO to google search and type '9702 physics reference' followed by the first few lines for the question.

      If the question has already been solved, you should obtain the result.

      Delete
  21. can u post 2015 summer paper. Thanks

    ReplyDelete
    Replies
    1. Some of the questions are already solved. Try to look for them.

      Delete

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