Photoelectrons are electrons that are emitted from the surface of a material when it is exposed to light. This phenomenon is known as the photoelectric effect, which was a key discovery in the development of quantum mechanics.
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The energy of photoelectrons is determined by the frequency of the incident light, not its intensity.
Photoelectrons are emitted instantaneously upon exposure to light, with no observable delay.
The number of photoelectrons emitted is proportional to the intensity of the incident light.
The maximum kinetic energy of photoelectrons is independent of the intensity of the incident light.
The work function of a material determines the minimum energy required to eject a photoelectron.
Review Questions
Explain how the energy of photoelectrons is related to the frequency of the incident light.
According to the photoelectric effect, the energy of the emitted photoelectrons is directly proportional to the frequency of the incident light. This means that as the frequency of the light increases, the energy of the photoelectrons also increases. This relationship is described by the equation $E_k = hf - \phi$, where $E_k$ is the kinetic energy of the photoelectron, $h$ is Planck's constant, $f$ is the frequency of the light, and \phi is the work function of the material. The work function represents the minimum energy required to eject an electron from the material, so the higher the frequency of the light, the more energy the photoelectrons can gain.
Describe how the number of photoelectrons emitted is related to the intensity of the incident light.
The number of photoelectrons emitted is proportional to the intensity of the incident light. This means that as the intensity of the light increases, the number of photoelectrons emitted also increases. This is because the intensity of the light is a measure of the number of photons striking the surface of the material per unit area per unit time. With more photons striking the surface, there are more opportunities for photoelectrons to be emitted. However, the maximum kinetic energy of the photoelectrons is independent of the intensity of the light and is only determined by the frequency of the light and the work function of the material.
Analyze the significance of the instantaneous emission of photoelectrons and how it supports the wave-particle duality of light.
The instantaneous emission of photoelectrons upon exposure to light is a key observation that supports the wave-particle duality of light. If light were purely a wave phenomenon, one would expect to see a delay between the time the light strikes the material and the emission of photoelectrons, as the wave would need time to interact with the material and build up enough energy to eject an electron. However, the observed instantaneous emission of photoelectrons suggests that light behaves as discrete packets of energy, known as photons, that can directly transfer their energy to electrons in the material, causing them to be ejected immediately. This observation, along with other evidence, was crucial in the development of quantum mechanics and the understanding that light exhibits both wave-like and particle-like properties, known as the wave-particle duality.