科目：物理 Physics (9702)
年份：2013 冬季
试卷：Paper 43
总页数：20
章节：12-13: Circular Motion & Gravitational Fields, 14-16: Temperature, Ideal Gases & Thermodynamics, 18: Electric fields, 19: Capacitance, 20: Magnetic fields, 21: Alternating currents, 22: Quantum physics, 23: Nuclear physics, 24: Medical physics
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Section A
Answer all the questions in the spaces provided.
For Examiner's Use
1 (a) State Newton’s law of gravitation.
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(b) A star and a planet are isolated in space. The planet orbits the star in a circular orbit of radius $R$ , as illustrated in Fig. 1.1.
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Fig. 1.1
The angular speed of the planet about the star is $\omega$ .
By c5
(c) The Earth orbits the Sun in a circular orbit of radius $1.5 \times 10^8$ km. The mass of the Sun is $2.0 \times 10^{30}$ kg.
A distant star is found to have a planet that has a circular orbit about the star. The radius of the orbit is $6.0 \times 10^8$ km and the period of the orbit is 2.0 years.
Use the expression in (b) to calculate the mass of the star.
mass = …………………………… kg [3]
For Examiner’s Use
© UCLES 2013 9702/43/O/N/13 [Turn over6 2 (a) (i) State what is meant by the *internal energy* of a system. ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... [2] (ii) Explain why, for an ideal gas, the internal energy is equal to the total kinetic energy of the molecules of the gas. ............................................................................................................................... .....................................................................................
7 (ii) During the heating, the gas expands, doing $1.5 \times 10^3$ J of work. State the first law of thermodynamics. Use the law and your answer in (i) to determine the total energy supplied to the gas. ............................................................................................................... ............................................................................................................... total energy = ........................................... J [3] For Examiner’s Use © UCLES 2013 9702/43/O/N/13 [Turn over
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3 (a) Define *electric potential* at a point.
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(b) Two point charges A and B are separated by a distance of 20 nm in a vacuum, as illustrated in Fig. 3.1.
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Fig. 3.1
A point P is a distance $x$ from A along the line AB.
The variation with distance $x$ of the electric potential $V_A$ due to charge A alone is shown in Fig. 3.2.
<div st9 (i) State and explain whether the charges A and B are of the same, or opposite, sign. ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... [2] (ii) By reference to Fig. 3.2, state how the combined electric potential due to both charges may be determined. ............................................................................................................................... .............................................................................
10 4 (a) State two functions of capacitors connected in electrical circuits. 1. ............................................................................................................................... ............................................................................................................................ 2. ............................................................................................................................... ............................................................................................................................ [2] (b) Three capacitors are connected in parallel to a power supply as shown in Fig. 4.1. Fig. 4.1 The capacitors have capacitances $C_1$, $C_2$ and $C_3$. The power supply provides a potential differe
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(c) A student has available three capacitors, each of capacitance $12\,\mu\text{F}$ .
Draw circuit diagrams, one in each case, to show how the student connects the three capacitors to provide a combined capacitance of
(i) $8\,\mu\text{F}$ ,
(ii) $18\,\mu\text{F}$ .
For Examiner’s Use
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© UCLES 2013 9702/43/O/N/13 [Turn over12
5 A uniform magnetic field of flux density $B$ makes an angle $\theta$ with a flat plane PQRS, as shown in Fig. 5.1.
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Fig. 5.1
The plane PQRS has area $A$ .
(a) State
(i) what is meant by a magnetic field,
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(ii) an expression, in terms of $A$ , $B$ and $\theta$ , for the magnetic flux $\Phi$ through the plane PQRS.
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(b) A vertic13 (i) Explain why, when the window is opened, the change in magnetic flux linkage due to the vertical component of the Earth’s magnetic field is zero. ............................................................................................................................... ............................................................................................................................... [1] (ii) Calculate, for the window opening through an angle of 90°, the change in magnetic flux linkage. change in flux linkage = ........................................ Wb [2] (c) (i) State Faraday’s law of electromagnetic induction. ............................................................................................................................ .......................
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6 A particle has mass $m$ and charge $+q$ and is travelling with speed $v$ through a vacuum. The initial direction of travel is parallel to the plane of two charged horizontal metal plates, as shown in Fig. 6.1.
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Fig. 6.1
The uniform electric field between the plates has magnitude $2.8 \times 10^4 \, \text{V} \, \text{m}^{-1}$ and is zero outside the plates. The particle passes between the plates and emerges beyond them, as illustrated in Fig. 6.1.
(a) Explain why the path of the particle in the electric field is not an arc of a circle.
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(i) State and explain the direction of the magnetic field.
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(ii) The particle has speed $4.7 \times 10^5 \, \text{m} \, \text{s}^{-1}$ .
Calculate the magnitude of the magnetic flux density.
Explain your working.
magnetic flux density = ........................................ T [3]
(c) The particle in (b) has mass $m$ , charge $+q$ and speed $v$ .
Without any further calculation, state the effect16 7 (a) By reference to the photoelectric effect, explain (i) what is meant by work function energy, ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... [2] (ii) why, even when the incident light is monochromatic, the emitted electrons have a range of kinetic energy up to a maximum value. ............................................................................................................................... .........................................
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(i) Use Fig. 7.1 to determine the work function energy of the metal surface.
work function energy = ………………………………………… J [3]
(ii) A second metal has a greater work function energy than that in (i).
On Fig. 7.1, draw a line to show the variation with $f$ of $E_{\text{MAX}}$ for this metal. [2]
(iii) Explain why the graphs in (i) and (ii) do not depend on the intensity of the incident radiation.
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For Examiner’s Use
© UCLES 2013 9702/43/O/N/13 [Turn over18 BLANK PAGE © UCLES 2013 9702/43/O/N/13
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8 One possible nuclear fission reaction is
$$
{}^{235}_{92}\text{U} + {}^1_0\text{n} \rightarrow {}^{141}_{56}\text{Ba} + {}^{92}_{36}\text{Kr} + 3{}^1_0\text{n} + \text{energy}.
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Barium-141 ( ${}^{141}_{56}\text{Ba}$ ) and krypton-92 ( ${}^{92}_{36}\text{Kr}$ ) are both $\beta$ -emitters.
Barium-141 has a half-life of 18 minutes and a decay constant of $6.4 \times 10^{-4} \, \text{s}^{-1}$ .
The half-life of krypton-92 is 3.0 seconds.
(a) State what is meant by *decay constant*.
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...........................................20 Section B Answer all the questions in the spaces provided. For Examiner's Use 9 (a) State three properties of an ideal operational amplifier (op-amp). 1. ....................................................................................................................... 2. ....................................................................................................................... 3. ....................................................................................................................... [3] (b) An amplifier circuit is shown in Fig. 9.1. Fig. 9.1 (i) Calculate the gain of the amplifier circuit. gain = ........................................................... [2] © UCLES 2013 9702/43/O/N/13
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(ii) The variation with time $t$ of the input potential $V_{IN}$ is shown in Fig. 9.2.
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Fig. 9.2
On the axes of Fig. 9.2, show the variation with time $t$ of the output potential $V_{OUT}$ . [3]
For Examiner's Use
© UCLES 2013 9702/43/O/N/13 [Turn over]22 10 Magnetic resonance imaging (MRI) requires the use of a non-uniform magnetic field superimposed on a large uniform magnetic field. State and explain the purpose of (a) the large uniform magnetic field, ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... [3] (b) the non-uniform magnetic field. ................................
23 11 Data may be transmitted in either analogue or digital form. (a) State (i) what is meant by a *digital* signal, ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... [2] (ii) three advantages of the digital transmission of data when compared to analogue transmission. 1. ............................................................................................................................... 2. ......................................................