When radiations of wavelength ' λ ' is incident on a metallic surface the stopping potential required is 4.8 volt. If same surface is illuminated with radiations of double the wavelength, th

Question

When radiations of wavelength ' λ ' is incident on a metallic surface the stopping potential required is 4.8 volt. If same surface is illuminated with radiations of double the wavelength, then required stopping potential becomes 1.6 volt. Then the value of threshold wavelength for the surface is

TestHub · Accepted Answer

We know, V = λ hc ​ − ϕ 0 ​ ⇒ 4.8 = λ hc ​ − ϕ ....(i) Given λ = 2 λ ⇒ 1.6 = 2 λ h c ​ − ϕ ....(ii) ∴ Dividing (i) by (ii), 3 ( 2 λ hc ​ − ϕ ) = λ hc ​ − ϕ 3 2 λ hc ​ − 3 ϕ = ( λ hc ​ − ϕ ) 2 λ hc ​ = 2 ϕ ∴ Threshold wavelength is 4 λ

Physics - Modern Physics Question with Solution | TestHub

Options:

Doubts & Discussion