• 9702 November 2014 Paper 41 & 42 Worked Solutions | A-Level Physics

Paper 41 & 42

Question 1
{Detailed explanations for this question is available as Solution 444 at Physics 9702 Doubts | Help Page 85 - http://physics-ref.blogspot.com/2015/03/physics-9702-doubts-help-page-85.html}





Question 2
{Detailed explanations for this question is available as Solution 877 at Physics 9702 Doubts | Help Page 177 - http://physics-ref.blogspot.com/2015/07/physics-9702-doubts-help-page-177.html}





Question 3
{Detailed explanations for this question is available as Solution 924 at Physics 9702 Doubts | Help Page 190 - http://physics-ref.blogspot.com/2015/08/physics-9702-doubts-help-page-190.html}




Question 4
A small ball rests at point P on a curved track of radius r, as shown in Fig. 4.1. ...





Question 5
{Detailed explanations for this question is available as Solution 619 at Physics 9702 Doubts | Help Page 122 - http://physics-ref.blogspot.com/2015/04/physics-9702-doubts-help-page-122.html}





Question 6
{Detailed explanations for this question is available as Solution 700 at Physics 9702 Doubts | Help Page 142 - http://physics-ref.blogspot.com/2015/05/physics-9702-doubts-help-page-142.html}





Question 7
{Detailed explanations for this question is available as Solution 919 at Physics 9702 Doubts | Help Page 188 - http://physics-ref.blogspot.com/2015/08/physics-9702-doubts-help-page-188.html}





Question 8
{Detailed explanations for this question is available as Solution 1051 at Physics 9702 Doubts | Help Page 220 - http://physics-ref.blogspot.com/2015/10/physics-9702-doubts-help-page-220.html}





Question 9
{Detailed explanations for this question is available as Solution 1107 at Physics 9702 Doubts | Help Page 237 - http://physics-ref.blogspot.com/2016/04/physics-9702-doubts-help-page-237.html}




Question 10
An ideal operational amplifier (op-amp) has infinite open-loop gain and infinite input resistance (impedance)...



Question 11
The use of X-rays in medical diagnosis gives rise to an increased exposure of the patient to radiation.



Question 12
A station on Earth transmits a signal of initial power 3.1 kW to a geostationary satellite.  The attenuation of the signal received by the satellite is 190 dB.




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.

• 9702 June 2009 Paper 1 Worked Solutions | A-Level Physics

1 D                  11 A                21 A                31 D

2 C                  12 D                22 B                32 A

3 B                  13 B                23 C                33 B

4 B                  14 C                24 B                34 D

5 D                  15 B                25 A                35 D

6 C                  16 C                26 B                36 B

7 A                  17 B                27 A                37 B

8 C                  18 D                28 B                38 C

9 B                  19 A                29 D                39 C

10 C                20 D                30 A                40 D

Notes for some specific questions:



2 - Ans: C. {Detailed explanations for this question is available as Solution 791 at Physics 9702 Doubts | Help Page 159 - http://physics-ref.blogspot.com/2015/06/physics-9702-doubts-help-page-159.html}



4 - Ans: B. {Detailed explanations for this question is available as Solution 1086 at Physics 9702 Doubts | Help Page 230 - http://physics-ref.blogspot.com/2015/12/physics-9702-doubts-help-page-230.html}


5 - Ans: D. {Detailed explanations for this question is available as Solution 918 at Physics 9702 Doubts | Help Page 188 - http://physics-ref.blogspot.com/2015/08/physics-9702-doubts-help-page-188.html}


6 - Ans: C. {Detailed explanations for this question is available as Solution 1057 at Physics 9702 Doubts | Help Page 222 - http://physics-ref.blogspot.com/2015/11/physics-9702-doubts-help-page-222.html}


7 - Ans: A. {Detailed explanations for this question is available as Solution 150 at Physics 9702 Doubts | Help Page 26 - http://physics-ref.blogspot.com/2014/11/physics-9702-doubts-help-page-26.html}


8 - Ans: C. {Detailed explanations for this question is available as Solution 1078 at Physics 9702 Doubts | Help Page 227 - http://physics-ref.blogspot.com/2015/12/physics-9702-doubts-help-page-227.html}


10 - Ans: C. {Detailed explanations for this question is available as Solution 321 at Physics 9702 Doubts | Help Page 55 - http://physics-ref.blogspot.com/2015/01/physics-9702-doubts-help-page-55.html}


11 - Ans: A. {Detailed explanations for this question is available as Solution 325 at Physics 9702 Doubts | Help Page 56 - http://physics-ref.blogspot.com/2015/01/physics-9702-doubts-help-page-56.html}



13 - Ans: B. {Detailed explanations for this question is available as Solution 71 at Physics 9702 Doubts | Help Page 13 - http://physics-ref.blogspot.com/2014/11/physics-9702-doubts-help-page-13.html}


14 - Ans: C. {Detailed explanations for this question is available as Solution 843 at Physics 9702 Doubts | Help Page 168 - http://physics-ref.blogspot.com/2015/06/physics-9702-doubts-help-page-168.html}


15 - Ans: B. {Detailed explanations for this question is available as Solution 64 at Physics 9702 Doubts | Help Page 12 - http://physics-ref.blogspot.com/2014/11/physics-9702-doubts-help-page-12.html}



18 - Ans: D. {Detailed explanations for this question is available as Solution 284 at Physics 9702 Doubts | Help Page 48 - http://physics-ref.blogspot.com/2015/01/physics-9702-doubts-help-page-48.html}


19 - Ans: A. {Detailed explanations for this question is available as Solution 939 at Physics 9702 Doubts | Help Page 193 - http://physics-ref.blogspot.com/2015/09/physics-9702-doubts-help-page-193.html}


20 - Ans: D. {Detailed explanations for this question is available as Solution 881 at Physics 9702 Doubts | Help Page 178 - http://physics-ref.blogspot.com/2015/07/physics-9702-doubts-help-page-178.html}


21 - Ans: A. {Detailed explanations for this question is available as Solution 298 at Physics 9702 Doubts | Help Page 50 - http://physics-ref.blogspot.com/2015/01/physics-9702-doubts-help-page-50.html}


24 - Ans: B. {Detailed explanations for this question is available as Solution 1105 at Physics 9702 Doubts | Help Page 236 - http://physics-ref.blogspot.com/2016/03/physics-9702-doubts-help-page-236.html}


25 - Ans: A. {Detailed explanations for this question is available as Solution 381 at Physics 9702 Doubts | Help Page 69 - http://physics-ref.blogspot.com/2015/02/physics-9702-doubts-help-page-69.html}



28 - Ans: B. {Detailed explanations for this question is available as Solution 1052 at Physics 9702 Doubts | Help Page 221 - http://physics-ref.blogspot.com/2015/11/physics-9702-doubts-help-page-221.html}


29 - Ans: D. {Detailed explanations for this question is available as Solution 681 at Physics 9702 Doubts | Help Page 137 - http://physics-ref.blogspot.com/2015/05/physics-9702-doubts-help-page-137.html}


31 - Ans: D. {Detailed explanations for this question is available as Solution 1108 at Physics 9702 Doubts | Help Page 237 - http://physics-ref.blogspot.com/2016/04/physics-9702-doubts-help-page-237.html}


33 - Ans: B. {Detailed explanations for this question is available as Solution 964 at Physics 9702 Doubts | Help Page 199 - http://physics-ref.blogspot.com/2015/09/physics-9702-doubts-help-page-199.html}



39 - Ans: C. {Detailed explanations for this question is available as Solution 962 at Physics 9702 Doubts | Help Page 198 - http://physics-ref.blogspot.com/2015/09/physics-9702-doubts-help-page-198.html}



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. 

• 9702 November 2014 Paper 23 Worked Solutions | A-Level Physics

Paper 23

Question 2
{Detailed explanations for this question is available as Solution 680 at Physics 9702 Doubts | Help Page 137 - http://physics-ref.blogspot.com/2015/05/physics-9702-doubts-help-page-137.html}





Question 3
{Detailed explanations for this question is available as Solution 897 at Physics 9702 Doubts | Help Page 183 - http://physics-ref.blogspot.com/2015/08/physics-9702-doubts-help-page-183.html}





Question 4
{Detailed explanations for this question is available as Solution 953 at Physics 9702 Doubts | Help Page 197 - http://physics-ref.blogspot.com/2015/09/physics-9702-doubts-help-page-197.html}





Question 6
{Detailed explanations for this question is available as Solution 696 at Physics 9702 Doubts | Help Page 141 - http://physics-ref.blogspot.com/2015/05/physics-9702-doubts-help-page-141.html}





Question 7
Explain what is meant by a progressive transverse wave.


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.

• Physics 9702 Doubts | Help Page 176

Question 874: [Current of Electricity]

A car battery has internal resistance of 0.060 Ω. It is re-charged using a battery charger having an e.m.f. of 14 V and an internal resistance of 0.10 Ω, as shown in Fig.1.

(a) At beginning of the re-charging process, current in circuit is 42 A and e.m.f. of the battery is E (measured in volts).

(i) For the circuit of Fig.1, state

1. magnitude of the total resistance

2. total e.m.f. in the circuit. Give answer in terms of E

(ii) Use answers to (i) and data from the question to determine the e.m.f. of the car battery at the beginning of the re-charging process

(b) For majority of the charging time of the car battery, e.m.f. of the car battery is 12 V and the charging current is 12.5 A. Battery is charged at this current for 4.0 hours. Calculate, for this charging time,

(i) charge that passes through the battery

(ii) energy supplied from the battery charger

(iii) total energy dissipated in the internal resistance of battery charger and the car battery

(c) Use answers in (b) to calculate the percentage efficiency of transfer of energy from the battery charger to stored energy in the car battery

Reference: Past Exam Paper – June 2007 Paper 2 Q6

Solution 874:

(a)

(i)

1. Total resistance (= 0.060 + 0.10) = 0.16Ω

2. Total e.m.f. = EITHER (14 – E)     OR (E – 14)

{The difference of the 2 e.m.f. is taken since they are in opposite direction – the flows of current [which is from the positive terminal] from the batteries are in opposite directions – polarities of the battery are opposite. AND either of the 2 answer are accepted since we do not yet know whether E is greater or less than 14V. But logically, current should be flowing from a battery charger to the battery – not the reverse.}

(ii)

{At beginning of re-charging, the current of 42A is from the charger. So, for total emf = (14 – E), the current is taken in the positive direction. For (E – 14), current is taken as a negative value.}

EITHER 14 – E = 42 × 0.16               OR E – 14 = -42 × 0.16

e.m.f. E of the car battery = 7.3V

(b)

(i) Charge, Q = It = 12.5 × (4×60×60) = 1.8×10⁵C

(ii)

{Power = Energy / time. Energy = Power × time}

EITHER Energy = EQ           OR Energy = EIt

Energy = 14 × (1.8×10⁵)         OR Energy = 14 × 12.5 × (4×3600)

Energy = 2.52×10⁶J

(iii)

{Power, P = I²R or Power = VI}

Energy dissipated = I²Rt                    OR VIt and V = IR

Energy dissipated = (12.5²) × (0.16) × (4×3600) = 3.6×10⁵J

(c)

{Energy supplied = 2.52×10⁶J. Wasted energy (in internal resistance) = 3.6×10⁵J.

Useful energy = Energy supplied – Wasted Energy

Efficiency = Useful energy / Total energy supplied}

Percentage efficiency = [(2.52×10⁶) – (3.6×10⁵)] / (2.52×10⁶) = 86%

Question 875: [Measurement > Uncertainty]

An experiment is carried out to measure resistance of a wire.

Current in the wire is (1.0 ± 0.2) A and potential difference across the wire is (8.0 ± 0.4) V.

What is the resistance of the wire and its uncertainty?

A (8.0 ± 0.2) Ω

B (8.0 ± 0.6) Ω

C (8 ± 1) Ω

D (8 ± 2) Ω

Reference: Past Exam Paper – June 2014 Paper 11 Q4

Solution 875:

Answer: D.

Ohm’s law: V = IR

Resistance R = V / I = 8.0 / 1.0 = 8Ω

ΔR / R = ΔV/V + ΔI/I

Uncertainty in resistance, ΔR = R × (ΔV/V + ΔI/I) = 8 × ([0.4/8] + [0.2/1.0]) = ±2Ω

Question 876: [Pressure]

Diagram shows two vessels, P and Q, both with sides inclined at 45°.

Vessel P tapers outwards and vessel Q tapers inwards, as shown.

Both vessels contain a liquid. Depth of the liquid in the vessels is the same. The liquid in vessel P is twice as dense as the liquid in vessel Q.

What is the ratio

pressure due to the liquid on the base of P / pressure due to the liquid on the base of Q ?

A 2 / 1                         B √2 / 1                                   C 1 / √2                                   D 1 / 2

Reference: Past Exam Paper – June 2011 Paper 12 Q20

Solution 876:

Answer: A.

Pressure P = hρg

The pressure P depends only on the depth h, the density ρ of the liquid, and the acceleration of free fall. The volume of the container does not affect the pressure at a point.

Let the density of the liquid in vessel Q = ρ

The depth h of the liquid in the vessels is the same.

For vessel P: Pressure P = h(ρ2)g = 2hρg

For vessel Q: Pressure P = hρg

Ratio = 2hρg / hρg = 2 / 1