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22.2. Photoelectric effect
A subsection of Physics, 9702, through 22. Quantum physics
Listing 10 of 46 questions
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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With reference to the photoelectric effect, state what is meant by work function energy. The work function energy of a clean metal surface is 5.5 × 10–19 J. Electromagnetic radiation of wavelength 280 nm is incident on the metal surface. The metal is in a vacuum. Calculate: 1. the photon energy photon energy = J 2. the maximum speed vMAX of the electrons emitted from the surface. vMAX = m s–1 Explain why most of the emitted electrons will have a speed lower than vMAX. The electromagnetic radiation incident on the metal surface may change in intensity or in frequency. Complete by inserting either ‘increases’ or ‘decreases’ or ‘no change’ to describe the effects of the changes shown on the maximum speed and on the rate of emission of electrons. change maximum speed of electrons rate of emission of electrons reduced intensity at constant frequency increased frequency at constant intensity
9702_w19_qp_41
THEORY
2019
Paper 4, Variant 1
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With reference to the photoelectric effect, state what is meant by work function energy. The work function energy of a clean metal surface is 5.5 × 10–19 J. Electromagnetic radiation of wavelength 280 nm is incident on the metal surface. The metal is in a vacuum. Calculate: 1. the photon energy photon energy = J 2. the maximum speed vMAX of the electrons emitted from the surface. vMAX = m s–1 Explain why most of the emitted electrons will have a speed lower than vMAX. The electromagnetic radiation incident on the metal surface may change in intensity or in frequency. Complete by inserting either ‘increases’ or ‘decreases’ or ‘no change’ to describe the effects of the changes shown on the maximum speed and on the rate of emission of electrons. change maximum speed of electrons rate of emission of electrons reduced intensity at constant frequency increased frequency at constant intensity
9702_w19_qp_43
THEORY
2019
Paper 4, Variant 3
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Electromagnetic radiation is incident on a metal surface. It is observed that there is a minimum frequency of electromagnetic radiation below which emission of electrons does not occur. This observation provides evidence for a particulate nature of electromagnetic radiation. State two other observations associated with photoelectric emission that provide evidence for a particulate nature of electromagnetic radiation. 1. 2. The maximum kinetic energy EMAX of electrons emitted from a metal surface is determined for different wavelengths λ of the electromagnetic radiation incident on the surface. The variation with 1 λ of EMAX is shown in . 1.9 2.0 2.1 2.2 2.3 2.4 / 106 m–1 λ 0.2 0.4 EMAX / eV 0.6 Use to determine the threshold frequency f0. f0 = Hz Use the gradient of the line on to determine a value for the Planck constant h. Explain your working. h = J s The electromagnetic radiation is now incident on a metal with a larger work function energy than the metal in . On , sketch the variation with 1 λ of EMAX.
9702_w20_qp_42
THEORY
2020
Paper 4, Variant 2
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State what is meant by: the photoelectric effect work function energy. A polished calcium plate in a vacuum is investigated by illuminating the surface with light. It is found that no photoelectric current is produced when the frequency of the light is less than 6.93 × 1014 Hz. State the name of the frequency below which no photoelectric current is produced. Explain how the photon model of electromagnetic radiation accounts for this phenomenon. Calculate the work function energy, in eV, of calcium. work function energy = eV
9702_w21_qp_42
THEORY
2021
Paper 4, Variant 2
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Questions Discovered
46