The maximum kinetic energy of the emitted photoelectrons depend on the:

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Photoelectric Effect:

• When the light of a sufficiently small wavelength is incident on the metal surface, electrons are ejected from the metal instantly. This phenomenon is called the photoelectric effect.​
• Einstein’s equation of photoelectric equation:

⇒ KEmax = hν - ϕo

Where h = Planck's constant, ν = frequency of incident radiation, ϕo = work function, and KEmax = maximum kinetic energy of electrons.

​Laws of Photoelectric Effect:

1. For a light of any given frequency; (f > fTh) photoelectric current is directly proportional to the intensity of light
2. For any given material, there is a certain minimum frequency, called threshold frequency, below which the emission of photoelectrons stops completely, no matter how high is the intensity of incident light.
3. The maximum kinetic energy of the photoelectrons is found to increase with the increase in the frequency of incident light when the frequency of incident radiation (f > fTh) exceeds the threshold limit. The maximum kinetic energy is independent of the intensity of light.
4. The photoelectric emission is an instantaneous process without any apparent time lag (10-9 sec or less), even when the intensity of the incident radiation is made extremely low.​​