科目：物理 Physics (9702)
年份：2024 夏季
试卷：Paper 41
总页数：20
章节：12-13: Circular Motion & Gravitational Fields, 14-16: Temperature, Ideal Gases & Thermodynamics, 17: Oscillations, 18: Electric fields, 19: Capacitance, 20: Magnetic fields, 21: Alternating currents, 22: Quantum physics, 23: Nuclear physics, 24: Medical physics, 25: Astronomy and cosmology
4 1 (a) Define gravitational potential at a point. ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... [2] (b) A satellite $X$ , of mass $M$ , orbits a planet at a constant distance $4R$ from the centre of the planet, as shown in Fig. 1.1.  Fig. 1.1 (not to scale) A second satellite $Y$ , of mass $2M$ , orbits the planet with orbital radius $R$ . The gravitational potential at $X$ due to the planet is $-\phi$ . The planet is a uniform
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(iii) Complete Table 1.1 by giving expressions, in terms of some or all of $M$ , $R$ and $\phi$ , for the quantities indicated for each of the satellites X and Y.
Table 1.1
<table>
<tr>
<th></th>
<th>satellite X</th>
<th>satellite Y</th>
</tr>
<tr>
<td>gravitational field strength at satellite due to planet</td>
<td></td>
<td></td>
</tr>
<tr>
<td>gravitational potential energy of satellite</td>
<td></td>
<td></td>
</tr>
</table>
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© UCLES 2024 9702/41/M/J/24 [Turn over6 2 (a) (i) State the magnitude and unit of absolute zero on the thermodynamic temperature scale. ................................................................................................................... [1] (ii) Explain why temperature measured using a laboratory liquid-in-glass thermometer does not give a measurement of thermodynamic temperature. ................................................................................................................... [1] (b) Fig. 2.1 shows a simplified diagram of a type of thermometer called a platinum resistance thermometer. <!-- Image: Fig. 2.1 --> Fig. 2.1 The glass tube is immersed in the environment for which the temperature is to be determined. The resistance between the terminals X and Y is measured. Fig. 2.2 shows t
7 (i) Explain how Fig. 2.2 shows that platinum is a suitable metal for use in a resistance thermometer. ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... [2] (ii) Suggest a reason why a platinum resistance thermometer is not suitable for measuring a rapidly changing temperature. ............................................................................................................................... ...................................................
8 3 (a) (i) State what is meant by an ideal gas. ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... [2] (ii) Use one of the basic assumptions of the kinetic theory to explain what can be deduced about the potential energy associated with the random motion of molecules in an ideal gas. ............................................................................................................................... ..............................................
9 (c) The volume $V$ of the gas in (b) is now varied, keeping its pressure constant. On Fig. 3.1, sketch the variation with $V$ of the internal energy $U$ of the gas. Fig. 3.1 2 © UCLES 2024 9702/41/M/J/24 [Turn over
10 4 (a) State what is meant by resonance. ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... [2] (b) A small ball is held in place using a stretched string. One end of the string is fixed to a wall and the other end is attached to a vibration generator, as shown in Fig. 4.1. vibration generator ball string wall Fig. 4.1 Initially, the vibration generator is switched off. A student displaces the ball vertically and then releases it. Fig. 4.2 shows the
11 (i) State the name of the phenomenon illustrated by the decrease in the amplitude of the oscillations in Fig. 4.2. ........................................................................................................................... [1] (ii) Explain the decrease with time of the amplitude of the oscillations of the ball. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... [2] (iii) Determine the frequency of the oscillations of the ball. frequency = .........
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5 (a) Define electric field.
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............................................................................................................................... [2]
(b) Fig. 5.1 shows two parallel conducting plates that are in a vacuum. The plates are separated by a distance of 6.7 cm and have a potential difference (p.d.) of 430 V between them.
conducting plate
+430 V
electron, speed $2.6 \times 10^7 \, \text{m} \, \text{s}^{-1}$
conducting plate
0 V
6.7 cm
Fig. 5.1
(i) On Fig. 5.1, draw four field lines to represent the elec13 (c) A uniform magnetic field is now applied in the region of the electric field in Fig. 5.1, so that the electron in (b)(iii) travels undeviated through the region. (i) Determine the direction of the uniform magnetic field. ................................................................................................................... [1] (ii) Explain, with reference to the forces exerted by the two fields on the electron, why the path of the electron is undeviated. ................................................................................................................... ................................................................................................................... ................................................................................
14 6 Fig. 6.1 shows a capacitor of capacitance $C$ connected in series with a resistor of resistance $R$. Fig. 6.1 Initially the switch is open and there is a p.d. of 12 V across the capacitor. At time $t = 0$, the switch is closed so that there is a current $I$ in the resistor. Fig. 6.2 shows the variation of $I$ with $t$. Fig. 6.2 (a) Explain the shape of the line in Fig. 6.2. ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... .......................
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(b) Use Fig. 6.2 to determine:
(i) resistance $R$
$R = \underline{\hspace{5cm}} \Omega \ [2]$
(ii) the time constant $\tau$ of the circuit in Fig. 6.1.
$\tau = \underline{\hspace{5cm}} \text{s} \ [3]$
(c) Use your answers in (b) to determine capacitance $C$ .
$C = \underline{\hspace{5cm}} \text{F} \ [2]$
[Total: 10]
© UCLES 2024 9702/41/M/J/24 [Turn over16
7 A circuit contains a power supply that provides a sinusoidal alternating input voltage $V_{IN}$. There is an output voltage $V_{OUT}$ across a load resistor $R$, as shown in Fig. 7.1.
Fig. 7.1
(a) State the purpose of the circuit in Fig. 7.1.
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...............................................................................................................................
............................................................................................................................... [2]
(b) Fig. 7.2 shows the variation of $V_{OUT}$ with time $t$.
Fig. 7.2
© UCLES 2024 9702/41/M/J/2417
(i) The load resistor R has a resistance of $370\,\Omega$ .
Show that the maximum power dissipated in R is $0.22\,\text{W}$ .
[2]
(ii) On Fig. 7.3, sketch the variation with $t$ of the power $P$ dissipated in R.
Fig. 7.3
[3]
(iii) Calculate the mean power dissipated in R.
mean power = ………………………………………… W [1]
(c) The circuit of Fig. 7.1 is disconnected, and R is connected directly across the power supply.
Explain, without calculation, how the mean power now dissipated in R compares with the answer in (b)(iii).
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© UCLES 2024 9702/41/M/J/24 [Turn over18 8 (a) State what is meant by a photon. ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... [2] (b) Fig. 8.1 shows a tube in which X-rays are produced at a metal target.  Fig. 8.1 Particles are accelerated from the filament to the target by a constant high voltage applied across the terminals X and Y. (i) State the name of the particles. ...............................................................................................
19 (c) For an accelerating voltage of 32 kV in Fig. 8.1, determine: (i) the maximum energy, in MeV, of an X-ray photon produced at the target maximum photon energy = ……………………………………… MeV [1] (ii) the maximum momentum of an X-ray photon produced at the target maximum photon momentum = …………………………………… N s [2] (iii) the minimum wavelength of X-rays produced at the target. minimum wavelength = ………………………………………… m [3] (d) Explain why X-rays can be used to produce images of internal body structures that have good contrast. ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ………………………………………………………………………………………………………… ……………………………………………………………………………………………………… 3 © UCLES 2024 9702/41/M/J/24 [Turn over
20 9 (a) Define half-life of a radioactive isotope. ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... [1] (b) Radioactive isotope X decays to isotope Y. A sample contains only nuclei of X at time $t = 0$. Fig. 9.1 shows the variation with $t$ of the numbers of nuclei of X and of Y as the sample decays.  Fig. 9.1 (i) State the name of the quantity represented by the magnitude of the gradient of line X in Fig. 9.1. ..................
21 (ii) State three conclusions about X or Y that may be drawn from Fig. 9.1. The conclusions may be qualitative or quantitative. Use the space below for any working that you need. 1 ....................................................................................................................... ....................................................................................................................... 2 ....................................................................................................................... ....................................................................................................................... 3 ....................................................................................................................... ......
22 10 (a) (i) State what is meant by the luminosity of a star. ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... [2] (ii) Explain how a standard candle in a distant galaxy can be used to determine the distance of the galaxy from an observer. ............................................................................................................................... .........................................................................................
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