Light of frequency v falls on material of threshold frequency vo, Maximum kinetic energy of emitted electron is proportional to
ν - νo
ν
vo
A.
ν - νo
When light falls on a metallic surface, ejection of photoelectron results. In this process, conservation
of energy holds.
Thus, from the law of conservation of energy,
Energy imparted by the photon
= Maximum kinetic energy of the emitted electron + work function of the metal
⇒ hv = (KE)max +
but being threshold frequency.
∴
⇒ (KE)max ∝ v - vo