When a certain metallic surface is illuminated with mono chromatic light of wavelength `lambda`, the stopping potential for photoelectric current is `3V_(0)`. When the same surface is illuminated with light of wavelength `2lambda` the stopping potential is `V_(0)`. The threshold wavelength for this surface for photoelectric effect is.

Options

A. `4 lambda`
B. `2 lambda`
C. `6 lambda`
D. `3 lambda`

Answer

1

Explanation

`eV_(0)=hc[(1)/(lambda)-(1)/(lambda_(0))],3V_(0)=(hc)/(e)[(1)/(lambda)-(1)/(lambda_(0)],V_(0)=(he)/(e)[(1)/(2lambda)-(1)/(lambda_(0))`]
on dividing and solving `lambda_(0) = 4 lambda`.