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22. Quantum physics
A section of Physics, 9702
Listing 10 of 94 questions
[T The photoelectric effect may be summarised in terms of the word equation photon energy = work function energy + maximum kinetic energy of emitted electrons. Explain what is meant by a photon, why most electrons are emitted with kinetic energy less than the maximum. Light of constant intensity is incident on a metal surface, causing electrons to be emitted. State and explain why the rate of emission of electrons changes as the frequency of the incident light is increased. Use
9702_w06_qp_4
THEORY
2006
Paper 4, Variant 0
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By reference to the photoelectric effect, state what is meant by the threshold frequency. The surface of a zinc plate has a work function of 5.8 × 10–19 J. In a particular laboratory experiment, ultraviolet light of wavelength 120 nm is incident on the zinc plate. A photoelectric current I is detected. In order to view the apparatus more clearly, a second lamp emitting light of wavelength 450 nm is switched on. No change is made to the ultraviolet lamp. Using appropriate calculations, state and explain the effect on the photoelectric current of switching on this second lamp.
9702_w10_qp_43
THEORY
2010
Paper 4, Variant 3
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An explanation of the photoelectric effect includes the terms photon energy and work function energy. Explain what is meant by a photon, work function energy. In an experiment to investigate the photoelectric effect, a student measures the wavelength λ of the light incident on a metal surface and the maximum kinetic energy Emax of the emitted electrons. The variation with Emax of 1 λ is shown in . –1 –2 –3 –4 λ 1 / 106 m–1 Emax / 10–19 J The work function energy of the metal surface is Φ. State an equation, in terms of λ, Φ and Emax, to represent conservation of energy for the photoelectric effect. Explain any other symbols you use. Use your answer in and to determine 1. the work function energy Φ of the metal surface, Φ = J 2. a value for the Planck constant. Planck constant = J s
9702_w11_qp_43
THEORY
2011
Paper 4, Variant 3
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State what is meant by a photon. It has been observed that, where photoelectric emission of electrons takes place, there is negligible time delay between illumination of the surface and emission of an electron. State three other pieces of evidence provided by the photoelectric effect for the particulate nature of electromagnetic radiation. 1. 2. 3. The work function of a metal surface is 3.5 eV. Light of wavelength 450 nm is incident on the surface. Determine whether electrons will be emitted, by the photoelectric effect, from the surface.
9702_w12_qp_41
THEORY
2012
Paper 4, Variant 1
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State what is meant by a photon. It has been observed that, where photoelectric emission of electrons takes place, there is negligible time delay between illumination of the surface and emission of an electron. State three other pieces of evidence provided by the photoelectric effect for the particulate nature of electromagnetic radiation. 1. 2. 3. The work function of a metal surface is 3.5 eV. Light of wavelength 450 nm is incident on the surface. Determine whether electrons will be emitted, by the photoelectric effect, from the surface.
9702_w12_qp_42
THEORY
2012
Paper 4, Variant 2
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By reference to the photoelectric effect, explain what is meant by work function energy, why, even when the incident light is monochromatic, the emitted electrons have a range of kinetic energy up to a maximum value. Electromagnetic radiation of frequency f is incident on a metal surface. The variation with frequency f of the maximum kinetic energy EMAX of electrons emitted from the surface is shown in . f / 1015 Hz EMAX / 10 –18 J Use to determine the work function energy of the metal surface. work function energy = J A second metal has a greater work function energy than that in . On , draw a line to show the variation with f of EMAX for this metal. Explain why the graphs in and do not depend on the intensity of the incident radiation.
9702_w13_qp_43
THEORY
2013
Paper 4, Variant 3
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By reference to the photoelectric effect, state what is meant by the threshold frequency. Electrons are emitted from a metal surface when light of a particular wavelength is incident on the surface. Explain why the emitted electrons have a range of values of kinetic energy below a maximum value. The wavelength of the incident radiation is λ. The variation with 1/λ of the maximum kinetic energy EMAX of electrons emitted from a metal surface is shown in . 1.0 1.0 2.0 3.0 4.0 1.5 2.0 2.5 – 3.5 3.0 / 106 m–1 EMAX / 10–19 J h Use to determine, without reference to the work function energy, the threshold frequency f0. f0 = Hz Use your answer in to calculate the work function energy Φ. Φ = J Caesium metal has a work function energy of 2.2 × 10–19 J. On the axes of , sketch a graph to show the variation with 1/λ of EMAX for caesium metal.
9702_w15_qp_41
THEORY
2015
Paper 4, Variant 1
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By reference to the photoelectric effect, state what is meant by the threshold frequency. Electrons are emitted from a metal surface when light of a particular wavelength is incident on the surface. Explain why the emitted electrons have a range of values of kinetic energy below a maximum value. The wavelength of the incident radiation is λ. The variation with 1/λ of the maximum kinetic energy EMAX of electrons emitted from a metal surface is shown in . 1.0 1.0 2.0 3.0 4.0 1.5 2.0 2.5 – 3.5 3.0 / 106 m–1 EMAX / 10–19 J h Use to determine, without reference to the work function energy, the threshold frequency f0. f0 = Hz Use your answer in to calculate the work function energy Φ. Φ = J Caesium metal has a work function energy of 2.2 × 10–19 J. On the axes of , sketch a graph to show the variation with 1/λ of EMAX for caesium metal.
9702_w15_qp_42
THEORY
2015
Paper 4, Variant 2
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Explain what is meant by the photoelectric effect. One wavelength of electromagnetic radiation emitted from a mercury vapour lamp is 436 nm. Calculate the photon energy corresponding to this wavelength. energy = J Light from the lamp in is incident, separately, on the surfaces of caesium and tungsten metal. Data for the work function energies of caesium and tungsten metal are given in . metal work function energy / eV caesium tungsten 1.4 4.5 Calculate the threshold wavelength for photoelectric emission from caesium, threshold wavelength = nm tungsten. threshold wavelength = nm Use your answers in to state and explain whether the radiation from the mercury lamp of wavelength 436 nm will give rise to photoelectric emission from each of the metals. caesium: tungsten:
9702_w16_qp_41
THEORY
2016
Paper 4, Variant 1
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Explain what is meant by the photoelectric effect. One wavelength of electromagnetic radiation emitted from a mercury vapour lamp is 436 nm. Calculate the photon energy corresponding to this wavelength. energy = J Light from the lamp in is incident, separately, on the surfaces of caesium and tungsten metal. Data for the work function energies of caesium and tungsten metal are given in . metal work function energy / eV caesium tungsten 1.4 4.5 Calculate the threshold wavelength for photoelectric emission from caesium, threshold wavelength = nm tungsten. threshold wavelength = nm Use your answers in to state and explain whether the radiation from the mercury lamp of wavelength 436 nm will give rise to photoelectric emission from each of the metals. caesium: tungsten:
9702_w16_qp_43
THEORY
2016
Paper 4, Variant 3
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Questions Discovered
94