Question

Ejection of the photoelectron from metal in the photoelectric effect experiment can by stopped by
applying 0.5 V when the radiation of 250 nm is used. The work function of metal is

(2) 5.5 eV
(3) 4.5 eV
(4) 5 eV
(1) 4 eV​

Answer 1

Photoelectric Effect -

1/2 mv² = hv- hv°

where

m is the mass of the electron

u is the velocity associated with the ejected electron.

h is plank’s constant.

v is frequency of photon,

v° is threshold frequency of metal.

lambda= 250 nm = 2500 × 10^-10 Å

E = 12400/2500 =4.96eV

stopping potential = 0.5 eV

E=W° + hv

4.96=W°+0.5

W°= 4.46eV ~ 4.5eV