When light of wavelength is incident on a photosensitive surface the stopping potential is ' V '. When light of wavelength 3 is incident on same surface the stopping potential is V 6 . Then the threshold wavelength for the surface is

Step-by-step solution

aligned & ₁= , ( V ₀ )₁= V & ₂=3 , ( V ₀ )₂= V 6 aligned Photo electric equation is given by eV ₀= hc ( 1 - 1 ₀ )....(i) In first case, eV = hc ( 1 - 1 ₀ ) For second case, eV 6 = hc ( 1 3 - 1 ₀ ).....(ii) Dividing equation (i) by equation (ii), aligned 6 & = 1 - 1 ₀ 1 3 - 1 ₀ = 3 ₀- ₀-3 ₀ & =5 aligned