Q.

When UV light of wavelength 300 nm is incident on the metal surface having work function 2.13 eV, electron emission takes place. The stopping potential is     [2024]

1 4.1 V  
2 2 V  
3 4 V  
4 1.5 V  

Ans.

(2)       

            Energy incident on the metal surface,

            E=hcλ=1240300eVE=4.13eV

            Work function, ϕ=2.13eV

            E=ϕ+eVs=4.13eV-2.13eV=2eVsVs=2V