Pre-U Review: Quantum

Which of the following best describes a photon?

• an electron emitted from a metal surface by the action of light

• a unit of energy

• a positively-charged atomic particle

• a quantum of electromagnetic radiation

Which of the following graphs shows the variation of the energy E of a photon of light with its wavelength λ?

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The given list shows three energies: Which sequence has the energies in increasing order of magnitude?

• 1 2 3

• 1 3 2

• 2 1 3

• 2 3 1

Which of the following has the greatest energy content?

• 10² photons of wavelength 1 pm (𝛾-rays)

• 10⁵ photons of wavelength 2 nm (X-rays)

• 10⁶ photons of wavelength 5 µm (infra-red radiation)

• 10⁸ photons of wavelength 600 nm (yellow light)

After travelling through a vacuum, a photon of light enters a block of glass.

Which of the following correctly describes the changes to the energy of the photon?

• increases because its associated wavelength decreases

• decreases because the speed of the radiation decreases

• stays the same because the speed of the radiation and the associated wavelength do no change

• stays the same because the frequency of the radiation does not change

Which phenomenon cannot be explained by the wave theory?

• diffraction

• interference

• photoelectric emission

• polarisation

Which of the following about photoelectric emissions is true?

• No emission of electrons occurs for very low intensity illumination

• For a given metal there is a minimum frequency of radiation below which no emission occurs

• The velocity of the emitted electrons is proportional to the intensity of the incident radiation

• The number of electrons emitted per second is independent of the intensity of the incident radiation

Electrons are emitted when a monochromatic beam of red light falls on one electrode of a photo-cell. If the light beam is replaced by a monochromatic blue beam of the same power, which of the following quantities would decrease?

• The maximum kinetic energy of the electrons emitted

• The number of photons striking the metal per unit time

• The energy of each photon striking the electrode

• The work function of the metal

Photoelectrons may be emitted when electromagnetic radiation of frequency f falls on a particular metal surface. The given graph shows how the maximum kinetic energy E of these electrons varies with f. The experiment is then repeated using another metal of greater work function energy.

Which of the following graphs will be obtained?

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In an experiment on the photoelectric effect, light of various frequencies were used to illuminate metals X and Y, and the potential difference V required to stop the photoelectrons is measured.

The work function of Y is known to be greater than that of X.

Which of the following graphs correctly illustrates the expected results?

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