When the energy of the incident radiation is increased by `20 %` , kinetic energy of the photoelectrons emitted from a metal surface increased from `0.5 eV to 0.8 eV`. The work function of the metal is

Options

A. 1.3 eV
B. 1.5 eV
C. 0.65 eVs
D. `1.0` eV

Answer

D

Explanation

Given : `E_(2)=1.2E_(1),K_(1)=0.5 eV` and `K_(2)=0.8 eV`
From Einstein's equation,
`E_(1)=W_(0)+K_(1)=W_(0)+0.5` ...(1)
`E_(2)=1.2 E_(1)=W_(0)+0.8` ...(2)
`:.E_(2)-E_(1)=0.2E_(1)=0.3`
`:.E_(1)=3/2=1.5eV`
and from (1), `1.5=W_(0)+0.5`
`:.W_(0)=1 eV`