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Question
Define photoelectric effect.
Solution
The phenomenon of emission of electrons from a metal surface, when radiation of appropriate frequency is incident on it, is known as the photoelectric effect.
Explanation:
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The emitted electrons are called photoelectrons.
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The light must have a frequency greater than a threshold frequency (ν0) specific to the metal.
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The energy of the incident light is used to overcome the work function (ϕ) of the metal and release electrons.
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The kinetic energy of the emitted electrons is given by Einstein’s photoelectric equation:
hν = ϕ + Kmax
where:
- h = Planck’s constant
- ν = Frequency of incident light
- ϕ = Work function (minimum energy required to eject electrons)
- Kmax = Maximum kinetic energy of ejected electrons
The photoelectric effect provides evidence for the particle nature of light and led to the development of quantum mechanics.
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