9702_s13_qp_41
A paper of Physics, 9702
Questions:
12
Year:
2013
Paper:
4
Variant:
1
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1
State what is meant by a gravitational field. In the Solar System, the planets may be assumed to be in circular orbits about the Sun. Data for the radii of the orbits of the Earth and Jupiter about the Sun are given in . radius of orbit / km Earth Jupiter 1.50 × 108 7.78 × 108 State Newton’s law of gravitation. Use Newton’s law to determine the ratio gravitational field strength due to the Sun at orbit of Earth gravitational field strength due to the Sun at orbit of Jupiter . ratio = For Examiner’s Use The orbital period of the Earth about the Sun is T. Use ideas about circular motion to show that the mass M of the Sun is given by M = 4π2R 3 GT 2 where R is the radius of the Earth’s orbit about the Sun and G is the gravitational constant. Explain your working. The orbital period T of the Earth about the Sun is 3.16 × 107 s. The radius of the Earth’s orbit is given in . Use the expression in to determine the mass of the Sun. mass = kg
13. Gravitational fields  →  13.2. Gravitational force between point masses
13. Gravitational fields  →  13.3. Gravitational field of a point mass
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2
For Examiner’s Use State what is meant by an ideal gas. Two cylinders A and B are connected by a tube of negligible volume, as shown in . tap T tube cylinder A cylinder B 2.5 × 103 cm3 1.6 × 103 cm3 4.9 × 105 Pa 3.4 × 105 Pa 300 K Initially, tap T is closed. The cylinders contain an ideal gas at different pressures. Cylinder A has a constant volume of 2.5 × 103 cm3 and contains gas at pressure 3.4 × 105 Pa and temperature 300 K. Show that cylinder A contains 0.34 mol of gas. For Examiner’s Use Cylinder B has a constant volume of 1.6 × 103 cm3 and contains 0.20 mol of gas. When tap T is opened, the pressure of the gas in both cylinders is 3.9 × 105 Pa. No thermal energy enters or leaves the gas. Determine the final temperature of the gas. temperature = K By reference to work done and change in internal energy, suggest why the temperature of the gas in cylinder A has changed.
15. Ideal gases  →  15.2. Equation of state
16. Thermodynamics  →  16.2. The first law of thermodynamics
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3
For Examiner’s Use A ball is held between two fixed points A and B by means of two stretched springs, as shown in . ball A B The ball is free to oscillate along the straight line AB. The springs remain stretched and the motion of the ball is simple harmonic. The variation with time t of the displacement x of the ball from its equilibrium position is shown in . 2.0 1.0 –1.0 –2.0 0.2 0.4 0.6 1.2 t / s x / cm 0.8 1.0 Use to determine, for the oscillations of the ball, 1. the amplitude, amplitude = cm 2. the frequency. frequency = Hz For Examiner’s Use Show that the maximum acceleration of the ball is 5.2 m s–2. Use your answers in to plot, on the axes of , the variation with displacement x of the acceleration a of the ball. a / m s–2 x / 10–2 m For Examiner’s Use Calculate the displacement of the ball at which its kinetic energy is equal to one half of the maximum kinetic energy. displacement = cm
17. Oscillations  →  17.1. Simple harmonic oscillations
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For Examiner’s Use Define electric potential at a point. A charged particle is accelerated from rest in a vacuum through a potential difference V. Show that the final speed v of the particle is given by the expression v = 2Vq m ⎛ ⎞ ⎜ ⎟ ⎝ ⎠ where q m is the ratio of the charge to the mass (the specific charge) of the particle. A particle with specific charge +9.58 × 107 C kg–1 is moving in a vacuum towards a fixed metal sphere, as illustrated in . 2.5 × 105 m s–1 particle specific charge +9.58 × 107 C kg–1 metal sphere potential +470 V The initial speed of the particle is 2.5 × 105 m s–1 when it is a long distance from the sphere. The sphere is positively charged and has a potential of +470 V. Use the expression in to determine whether the particle will reach the surface of the sphere.
18. Electric fields  →  18.5. Electric potential
20. Magnetic fields  →  20.3. Force on a moving charge
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For Examiner’s Use Define the tesla. A long solenoid has an area of cross-section of 28 cm2, as shown in . solenoid area of cross-section 28 cm2 coil C 160 turns A coil C consisting of 160 turns of insulated wire is wound tightly around the centre of the solenoid. The magnetic flux density B at the centre of the solenoid is given by the expression B = μ0n I where I is the current in the solenoid, n is a constant equal to 1.5 × 103 m–1 and μ0 is the permeability of free space. Calculate, for a current of 3.5 A in the solenoid, the magnetic flux density at the centre of the solenoid, flux density = T For Examiner’s Use the flux linkage in the coil C. flux linkage = Wb State Faraday’s law of electromagnetic induction. The current in the solenoid in is reversed in direction in a time of 0.80 s. Calculate the average e.m.f. induced in coil C. e.m.f. = V
20. Magnetic fields  →  20.4. Magnetic fields due to currents
20. Magnetic fields  →  20.5. Electromagnetic induction
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For Examiner’s Use A simple transformer is illustrated in . input load resistor laminated iron core primary coil secondary coil State why the iron core is laminated, what is meant by an ideal transformer. An ideal transformer has 300 turns on the primary coil and 8100 turns on the secondary coil. The root-mean-square input voltage to the primary coil is 9.0 V. Calculate the peak voltage across the load resistor connected to the secondary coil. peak voltage = V
21. Alternating currents  →  21.1. Characteristics of alternating currents
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For Examiner’s Use Some data for the work function energy Φ and the threshold frequency f0 of some metal surfaces are given in . metal Φ / 10–19 J f0 / 1014 Hz sodium zinc platinum 3.8 5.8 9.0 5.8 8.8 State what is meant by the threshold frequency. Calculate the threshold frequency for platinum. threshold frequency = Hz Electromagnetic radiation having a continuous spectrum of wavelengths between 300 nm and 600 nm is incident, in turn, on each of the metals listed in . Determine which metals, if any, will give rise to the emission of electrons. When light of a particular intensity and frequency is incident on a metal surface, electrons are emitted. State and explain the effect, if any, on the rate of emission of electrons from this surface for light of the same intensity and higher frequency.
22. Quantum physics  →  22.2. Photoelectric effect
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For Examiner’s Use State what is meant by a nuclear fusion reaction. One nuclear reaction that takes place in the core of the Sun is represented by the equation 1 H + 1 H 2 He + energy. Data for the nuclei are given in . mass / u proton 1 1 H deuterium 2 1 H helium 3 2 He 1.00728 2.01410 3.01605 Calculate the energy, in joules, released in this reaction. energy = J The temperature in the core of the Sun is approximately 1.6 × 107 K. Suggest why such a high temperature is necessary for this reaction to take place.
23. Nuclear physics  →  23.1. Mass defect and nuclear binding energy
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9
Suggest electrical sensing devices, one in each case, that may be used to monitor changes in light intensity, the width of a crack in a welded joint, the intensity of an ultrasound beam. For Examiner’s Use A student designs the circuit of to detect changes in temperature in the range 0 °C to 100 °C. thermistor, resistance RT resistor, constant resistance R +V VOUT The resistance of the thermistor is RT and that of the resistor is R. The student monitors the potential difference VOUT. State and explain whether VOUT increases or decreases as the temperature of the thermistor increases, whether the change in VOUT varies linearly with the change in temperature of the thermistor.
9. Electricity  →  9.3. Resistance and resistivity
10. D.C. circuits  →  10.3. Potential dividers
14. Temperature  →  14.2. Temperature scales
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10
For Examiner’s Use 10 Distinguish between sharpness and contrast in X-ray imaging. sharpness: contrast: State two causes of loss of sharpness of an X-ray image. 1. 2. Data for the linear attenuation coefficient μ of X-ray photons are given in . μ / cm–1 bone muscle 2.85 0.95 A parallel beam of X-rays is incident, separately, on a thickness of 3.5 cm of bone and on a muscle of thickness 8.0 cm. Calculate the ratio intensity of X-ray beam transmitted through bone intensity of X-ray beam transmitted through muscle . ratio = For Examiner’s Use Use your answer in to suggest whether an X-ray image of the bone and muscle would show good or poor contrast.
24. Medical physics  →  24.2. Production and use of X-rays
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11
For Examiner’s Use 11 A radio station emits an amplitude-modulated wave for the transmission of music. State what is meant by an amplitude-modulated (AM) wave. Give two reasons why the transmitted wave is modulated, rather than transmitting the information signal directly as a radio wave. 1. 2. For Examiner’s Use The variation with frequency f of the amplitude A of the transmitted wave is shown in . f / kHz A For this transmission, determine the wavelength of the carrier wave, wavelength = m the bandwidth, bandwidth = kHz the maximum frequency, in Hz, of the transmitted audio signal. frequency = Hz
7. Waves  →  7.1. Progressive waves
8. Superposition  →  8.1. Stationary waves
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12
For Examiner’s Use 12 An optic fibre is used for the transmission of digital telephone signals. The power input to the optic fibre is 9.8 mW. The effective noise level in the receiver circuit is 0.36 μW, as illustrated in . 9.8 mW receiver circuit, noise 0.36 +W optic fibre 85 km input circuit The signal-to-noise ratio at the receiver must not fall below 28 dB. For this transmission without any repeater amplifiers, the maximum length of the optic fibre is 85 km. Calculate the minimum input signal power to the receiver. power = W Use your answer in to calculate the attenuation in the fibre. attenuation = dB Determine the attenuation per unit length of the fibre. attenuation per unit length = dB km–1
24. Medical physics  →  24.2. Production and use of X-rays
24. Medical physics  →  24.1. Production and use of ultrasound
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