The work function of a metal is
Correct answer: A. the minimum energy needed to remove an electron from its surface
- A. the minimum energy needed to remove an electron from its surface
- B. the energy of the incident photon
- C. the kinetic energy of the fastest emitted electron
- D. the total energy of all the electrons
Explanation
Work function is a property of the metal, usually quoted in electron volts, and metals such as caesium with low values emit electrons even in visible light while most need ultraviolet. Dividing the work function by Planck's constant gives the threshold frequency. It corresponds to electrons at the surface, which is why the equation gives the maximum rather than the typical kinetic energy.
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About Photons and the Particle Model of Light
The particle model treats light as photons with energy E equals hf and momentum related to wavelength. Questions involve the photoelectric effect, work function, threshold frequency, stopping potential and photon energy, while distinguishing particle behaviour from the wave description of interference and diffraction.
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