Question

In photoelectric experiment energy of 2.48 eV irradiates a photo sensitive material. The stopping potential was measured to be 0.5 V. Work function of the photo sensitive material is : 

(1) 0.5 eV 

(2) 1.68 eV 

(3) 2.48 eV 

(4) 1.98 eV

Answer 1

Correct option is : (4) 1.98 eV

\(\mathrm{eV}_{\mathrm{s}}=\mathrm{h} \nu-\phi\)

\(0.5 \mathrm{~V}=2.48-\phi\)  

work function \( (\phi)=2.48 \mathrm{~V}-0.5 \mathrm{~V}=1.98 \mathrm{~V}\)