The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface , having work function `5.01 eV` , when ultraviolet light of `200 nm` falls on it , must be

Options

A. 2.4 V
B. – 1.2 V
C. – 2.4 V
D. 1.2 V

Answer

D

Explanation

`k_(max) =(hc)/(lambda) - W = (hc)/(lambda) - 5 .0.1= (12375)/(lambda( "in" Å) ) - 5.01`
`= (12375)/( 2000) - 5.01 = 6.1875- 5.01 = 1.17775 ~= 1.2V`