Light of frequency v falls on meterial of threshold frequency `v_(0)`. Maximum kinetic energy of emitted electron is proportional to

Options

A. `v-v_(0)`
B. v
C. `sqrt(v-v_(0))`
D. `v_(0)`

Answer

A

Explanation

When light falls on a metallic suface, ejection of photoelectron results. In this process, conservation of energy holds.
Thus, from law of conservation of energy imparted by the photon
= maximum kinetic energy of the emitted electron + work function of the metal.
`or hv=(KE)_("max")+phi `
but `phi =hv_(0), v_(0)` being threshold frequency.
`therefore (KE)_("max")=hv-hv_(0)`
`or (KE)_("max") prop v-v_(0)`