When metal surface with 2.1 eV work function is irridated with photon of 6.0 eV energy.Value of stopping potential will be….

Options

A. `+8.1`
B. `-8.1V`
C. `+3.9V`
D. `-3.9 V`

Answer

D

Explanation

Maximum kinetic energy of electron emitted `(1)/(2)mv_(max)^(2)=hv-phi_(0)`
`therefore eV_(0)hv-phi_(0)[because (1)/(2)mv_(max)^(2)=eV_(0)`]
`therefore eV_(0)=(6.0-2.1)eV`
`therefore eV_(0)=3.9 eV`
Stopping potential is negative voltage.
`therefore V_(0)=-3.9V`