科目：物理 Physics (9702)
年份：2011 冬季
试卷：Paper 43
总页数：20
章节：12-13: Circular Motion & Gravitational Fields, 14-16: Temperature, Ideal Gases & Thermodynamics, 17: Oscillations, 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 The planet Mars may be considered to be an isolated sphere of diameter $6.79 \times 10^6$ m with its mass of $6.42 \times 10^{23}$ kg concentrated at its centre. A rock of mass 1.40 kg rests on the surface of Mars.
For this rock,
(a) (i) determine its weight,
weight = ……………………………… N [3]
(ii) show that its gravitational potential energy is $-1.77 \times 10^7$ J.
[2]
(b) Use the information in (a)(ii) to determine the speed at which the rock must leave the surface of Mars so that it will escape the gravitational attraction of the planet.
speed = ……………………………… m s⁻¹ [3]
© UCLES 2011
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(c) The mean translational kinetic energy $<E_K>$ of a molecule of an ideal gas is given by the expression
$$
<E_K> = \frac{3}{2}kT
$$
where $T$ is the thermodynamic temperature of the gas and $k$ is the Boltzmann constant.
(i) Determine the temperature at which the root-mean-square (r.m.s.) speed of hydrogen molecules is equal to the speed calculated in (b).
Hydrogen may be assumed to be an ideal gas.
A molecule of hydrogen has a mass of 2 u.
temperature = ………………………………………… K [2]
(ii) State and explain one reason why hydrogen molecules may escape from Mars at temperatures below that calculated in (i).
…………………………………………………………………………………………………………
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……………………………………………………………………………………………………… [2]
For Examiner’s Use
© UCLES 2011 9702/43/O/N/11 [6 2 (a) A resistance thermometer and a thermocouple thermometer are both used at the same time to measure the temperature of a water bath. Explain why, although both thermometers have been calibrated correctly and are at equilibrium, they may record different temperatures. ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... [2] (b) State (i) in what way the absolute scale of temperature differs from other temperature scales, ...............................
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3 (a) Define simple harmonic motion.
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(b) A horizontal plate is vibrating vertically, as shown in Fig. 3.1.
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Fig. 3.1
The plate undergoes simple harmonic motion with a frequency of $4.5 \, \text{Hz}$ and amplitude $3.0 \, \text{mm}$ .
A metal cube of mass $5.8 \, \text{g}$ rests on the plate.
Calculate, for the cube, the energy of os8 (ii) Calculate this amplitude of oscillation. amplitude = ........................................ m [2] For Examiner's Use © UCLES 2011 9702/43/O/N/11
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4 (a) State two functions of capacitors in electrical circuits.
1. ...............................................................................................................................
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2. ...............................................................................................................................
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[2]
(b) Three uncharged capacitors of capacitance $C_1$, $C_2$ and $C_3$ are connected in series, as shown in Fig. 4.1.
plate A
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o-----|-----|-----|-----o
C₁ C₂ 10
(c) A capacitor of capacitance $12\,\mu\mathrm{F}$ is charged using a battery of e.m.f. $9.0\,\mathrm{V}$ , as shown in Fig. 4.2.
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Fig. 4.2
Switch $S_1$ is closed and switch $S_2$ is open.
(i) The capacitor is now disconnected from the battery by opening $S_1$ .
Calculate the energy stored in the capacitor.
energy = ………………………………………… J [2]
(ii) The $12\,\mu\mathrm{F}$ capacitor is now connected to an uncharged capacitor of capacitance $20\,\mu\mathrm{F}$ by closing $S_2$ . Switch $S_1$ remains open.
The total energy now stored in the two capacitors is $1.82 \times 10^{-4}\,\mathrm{J}$ .
Suggest why this value is different from your answer in (i).
……………………………………………………………………………………………………… [1]
© UCLES 2011
9702/11
5 The components for a bridge rectifier are shown in Fig. 5.1.
<div style="display: flex; justify-content: space-between; align-items: center;">
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Fig. 5.1
(a) Complete the circuit of Fig. 5.1 by showing the connections of the supply and of the load to the diodes. [2]
(b) Suggest one advantage of the use of a bridge rectifier, rather than a single diode, for the rectification of alternating current.
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.............................................................................................................................12 6 (a) Define the tesla. ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... [3] (b) A charged particle of mass $m$ and charge $+q$ is travelling with velocity $v$ in a vacuum. It enters a region of uniform magnetic field of flux density $B$ as shown in Fig. 6.1. particle mass $m$ , charge $+q$ uniform magnetic field flux de
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(c) A uniform magnetic field is produced in the region PQRS, as shown in Fig. 6.2.
<div style="text-align: center;">
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Fig. 6.2
The magnetic field is normal to the page.
At point X, a gamma-ray photon interaction causes two particles to be formed. The paths of these particles are shown in Fig. 6.2.
(i) Suggest, with a reason, why each of the paths is a spiral, rather than the arc of a circle.
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........................................................................................................14 7 An explanation of the photoelectric effect includes the terms photon energy and work function energy. (a) Explain what is meant by (i) a photon, ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... [2] (ii) work function energy. ............................................................................................................................... ..................................................................................................
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(ii) Use your answer in (i) and Fig. 7.1 to determine
1. the work function energy $\phi$ of the metal surface,
$\phi = \underline{\hspace{5cm}} \text{ J [2]}$
2. a value for the Planck constant.
$\text{Planck constant} = \underline{\hspace{5cm}} \text{ Js [3]}$
For Examiner's Use
© UCLES 2011 9702/43/O/N/11 [Turn over16
8 Radon-222 is a radioactive element having a half-life of 3.82 days.
Radon-222, when found in atmospheric air, can present a health hazard. Safety measures should be taken when the activity of radon-222 exceeds 200 Bq per cubic metre of air.
(a) (i) Define radioactive decay constant.
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............................................................................................................................... [2]
(ii) Show that the decay constant of radon-222 is $2.1 \times 10^{-6} \, \text{s}^{-1}$ .
[1]
(b) A volume of $1.017 BLANK PAGE Please turn over for Section B. © UCLES 2011 9702/43/O/N/11 [Turn over
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Section B
Answer all the questions in the spaces provided.
9 (a) The resistance of a light-dependent resistor (LDR) is approximately $500\,\Omega$ in daylight.
Suggest an approximate value for the resistance of the LDR in darkness.
resistance = ………………………………………… $\Omega$ [1]
(b) An electronic light-meter is used to warn when light intensity becomes low.
A light-dependent resistor is connected into the circuit of Fig. 9.1.
+4.5 V ○ —— ●
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□ 1.7 kΩ
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+2.5 V ○ —— △ —— +9 V
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+ +
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-9 V P
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● ● R
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red green
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● ●19 10 Explain the principles of the generation and detection of ultrasound waves. ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... ............................................................................................................................... .......................................................................
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11 (a) Distinguish between *sharpness* and *contrast* in X-ray imaging.
sharpness: ...............................................................................................................
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contrast: ...............................................................................................................
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[2]
(b) A student investigates the absorption of X-ray radiation in a model arm. A cross-section of the model arm is shown in Fig. 11.1.
<div style="text-align: center;">
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Fig. 11.1
Parallel X-ray beams are directe21 (ii) BB. For Examiner's Use ratio = ………………………………………… [3] (c) State whether your answers in (b) would indicate that the X-ray image (i) is sharp, ………………………………………………………………………………… [1] (ii) has good contrast. ………………………………………………………………………………… [1] © UCLES 2011 9702/43/O/N/11 [Turn over
22 12 In a cellular phone network, a region is divided into a number of cells, each with its own base station. (a) Suggest and explain two reasons why a region is divided into a number of cells. 1. ............................................................................................................................... ............................................................................................................................ ............................................................................................................................ 2. ............................................................................................................................ .........................................................................................
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