9702_w16_qp_42
A paper of Physics, 9702
Questions:
14
Year:
2016
Paper:
4
Variant:
2
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1
Define gravitational field strength. The nearest star to the Sun is Proxima Centauri. This star has a mass of 2.5 × 1029 kg and is a distance of 4.0 × 1013 km from the Sun. The Sun has a mass of 2.0 × 1030 kg. State why Proxima Centauri may be assumed to be a point mass when viewed from the Sun. Calculate 1. the gravitational field strength due to Proxima Centauri at a distance of 4.0 × 1013 km, field strength = N kg–1 2. the gravitational force of attraction between the Sun and Proxima Centauri. force = N Suggest quantitatively why it may be assumed that the Sun is isolated in space from other stars.
13. Gravitational fields  →  13.4. Gravitational potential
13. Gravitational fields  →  13.3. Gravitational field of a point mass
13. Gravitational fields  →  13.2. Gravitational force between point masses
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2
The equation of state for an ideal gas of volume V at pressure p is pV = nRT where R is the molar gas constant. State what is meant by the symbol n, the symbol T. An ideal gas is held in a container of volume 2.4 × 103 cm3 at pressure 4.9 × 105 Pa. The temperature of the gas is 100 °C. Show that the number of molecules of the gas in the container is 2.3 × 1023. Use data from to estimate the mean distance between molecules in the gas. mean distance = cm
15. Ideal gases  →  15.2. Equation of state
15. Ideal gases  →  15.3. Kinetic theory of gases
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4
A mass hangs vertically from a fixed point by means of a spring, as shown in . spring mass l The mass is displaced vertically and then released. The subsequent oscillations of the mass are simple harmonic. The variation with time t of the length l of the spring is shown in . 0.1 t / s 0.2 0.3 0.4 0.5 0.6 l / cm Use to state two values of t at which the mass is moving downwards with maximum speed, t = s and t = s determine, for these oscillations, the angular frequency ω, ω = rad s–1 show that the maximum speed of the mass is 0.42 m s–1. Use data from and to sketch, on the axes of , the variation with displacement x from the equilibrium position of the velocity v of the mass. 0.5 0.1 –0.1 –0.2 –0.3 –0.4 –0.5 0.2 0.3 0.4 –4 –3 –2 –1 x / cm v / m s–1
17. Oscillations  →  17.1. Simple harmonic oscillations
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5
Ultrasound may be used to obtain information about internal body structures. Suggest why the ultrasound from the transducer is pulsed. State what is meant by specific acoustic impedance. A parallel beam of ultrasound of intensity I0 is incident normally on the boundary between two media, as shown in . incident beam intensity I0 transmitted beam intensity IT specific acoustic impedance Z1 specific acoustic impedance Z2 The media have specific acoustic impedances Z1 and Z2. The intensity of the ultrasound beam transmitted across the boundary is IT. Explain the significance of the magnitudes of Z1 and of Z2 on the ratio IT / I0.
24. Medical physics  →  24.1. Production and use of ultrasound
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6
Two solid metal spheres A and B, each of radius 1.5 cm, are situated in a vacuum. Their centres are separated by a distance of 20.0 cm, as shown in . P sphere A sphere B x 20.0 cm 1.5 cm 1.5 cm (not to scale) Both spheres are positively charged. Point P lies on the line joining the centres of the two spheres, at a distance x from the centre of sphere A. The variation with distance x of the electric field strength E at point P is shown in . –10 –20 –30 –40 –50 x / cm E / N C–1 Use to determine the ratio magnitude of charge on sphere A magnitude of charge on sphere B . Explain your working. ratio = The variation with distance x of the electric potential V at point P is shown in . 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 V / V x / cm An α-particle is initially at rest on the surface of sphere A. The α-particle moves along the line joining the centres of the two spheres. Determine, for the α-particle as it moves between the two spheres, its maximum speed, maximum speed = m s–1 its speed on reaching the surface of sphere B. speed = m s–1
18. Electric fields  →  18.3. Electric force between point charges
18. Electric fields  →  18.5. Electric potential
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7
Define capacitance. Use the expression for the electric potential due to a point charge to show that an isolated metal sphere of diameter 25 cm has a capacitance of 1.4 × 10–11 F. Three capacitors of capacitances 2.0 μF, 3.0 μF and 4.0 μF are connected as shown in to a battery of e.m.f. 9.0 V. 4.0 μF 2.0 μF 3.0 μF 9.0 V Determine the combined capacitance of the three capacitors, capacitance = μF the potential difference across the capacitor of capacitance 3.0 μF, potential difference = V the positive charge stored on the capacitor of capacitance 2.0 μF. charge = μC
19. Capacitance  →  19.1. Capacitors and capacitance
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8
A circuit incorporating an ideal operational amplifier (op-amp) is shown in . +9 V –9 V VIN – + 10 kΩ 100 Ω RA RB 50 kΩ V The supply to the op-amp is +9 V / –9 V. The output of the amplifier is measured using a voltmeter having a range 0 – 5.0 V. A switch enables the inverting input to the op-amp to be connected to either resistor RA or resistor RB. A positive potential +VIN is applied to the input to the circuit. On , mark with the letter P the positive connection of the voltmeter such that the voltmeter shows a positive reading. Calculate the potential VIN such that the voltmeter has a full-scale deflection when the inverting input to the op-amp is connected to resistor RA of resistance 100 Ω, VIN = V resistor RB of resistance 10 kΩ. VIN = V Suggest a use for this type of circuit.
10. D.C. circuits  →  10.3. Potential dividers
10. D.C. circuits  →  10.1. Practical circuits
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9
A stiff wire is held horizontally between the poles of a magnet, as illustrated in . S N stiff wire When a constant current of 6.0 A is passed through the wire, there is an additional downwards force on the magnet of 0.080 N. On , draw an arrow on the wire to show the direction of the current in the wire. Explain your answer. The constant current of 6.0 A is now replaced by a low-frequency sinusoidal current. The root-mean-square (r.m.s.) value of this current is 2.5 A. Calculate the difference between the maximum and the minimum forces now acting on the magnet. difference = N
20. Magnetic fields  →  20.4. Magnetic fields due to currents
20. Magnetic fields  →  20.2. Force on a current-carrying conductor
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11
State Faraday’s law of electromagnetic induction. An alternating current is passed through an air-cored solenoid. An iron core is inserted into the solenoid and then held stationary within the solenoid. The current in the solenoid is now smaller. Explain why the root-mean-square (r.m.s.) value of the current in the solenoid is reduced as a result of inserting the core. Practical transformers are very efficient. However, there are some power losses. State two sources of power loss within a transformer. 1. 2.
20. Magnetic fields  →  20.4. Magnetic fields due to currents
20. Magnetic fields  →  20.5. Electromagnetic induction
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12
State an effect, one in each case, that provides evidence for the wave nature of a particle, the particulate nature of electromagnetic radiation. Four electron energy levels in an isolated atom are shown in . energy –0.54 eV –0.85 eV –1.51 eV –3.40 eV For the emission spectrum associated with these energy levels, on , mark with an arrow the transition that gives rise to the shortest wavelength, show that the wavelength of the transition in is 4.35 × 10–7 m. State what is meant by the de Broglie wavelength. Calculate the speed of an electron having a de Broglie wavelength equal to the wavelength in . speed = m s–1
22. Quantum physics  →  22.3. Wave-particle duality
22. Quantum physics  →  22.1. Energy and momentum of a photon
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14
Phosphorus-30 (30 15P) was the first artificial radioactive nuclide to be produced in a laboratory. This was achieved by bombarding aluminium-27 (27 13Al) with α-particles. A partial nuclear equation to represent this reaction is 13Al + α → 30 15P + Φ State the full nuclear notation for the α-particle, the particle represented by the symbol Φ. Data for the rest masses of the particles in the reaction are given in . particle mass / u 13Al α 15P Φ 26.98153 4.00260 29.97830 1.00867 Calculate, for this reaction, the change in the total rest mass of the particles, mass change = u the energy, in joule, equivalent to the mass change calculated in . energy = J With reference to your answer in , comment on the energy of the α-particle such that the reaction can take place.
23. Nuclear physics  →  23.1. Mass defect and nuclear binding energy
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