Light described at a place by te equation `E=(100 V/m) [sinxx(10^15 s ^(-1) t) +sin (8xx 10^15 s^(-1) t)]` falls on a metal surface having work function 2.0 eV. Calculate the maximum kinetic energy of the photoelectrons.

Options

A. 5.27 eV
B. 31.28 eV
C. 3.28 eV
D. 15.5 eV

Answer

C

Explanation

The light contains two different frequencies. The one with larger frequency will cause photoelectrons with largest kinetic energy . This larger frequency is
`upsilon = (omega)/(2 pi) = (8 xx 10^(15) s^(-1))/(2pi)`
The maximum kinetic energy of the photoelectrons is
`K_(max) - h upsilon - phi`
`=(4.14 xx 10^(-15) eVs) xx ((8 xx 10^15)/(2pi)s^(-1)) -2.0 eV`
`= 5.27 eV -2.0 eV= 3.28 eV`