When a certain metallic surface is illuminated with monochromatic light wavelength , the stopping potential for photoelectric current is 4 V₀ . When the same surface is illuminated with light of wavelength 3 , the stopping potential is V ₀ . The threshold wavelength for this surface for photoelectric effect is

Step-by-step solution

Using Einstein's photoelectric equation, h v= ₀+ KE _ max hc = ₀+ e (4 ~V ₀ ) ....(i) ( KE _ = eV _ s ) Also, hc 3 = ₀+ eV ₀ ...(ii) Subtracting equation (i) from 4 equation (ii) we get, ( 4 3 -1 ) hc =4 ₀- ₀ or ₀= hc 9 But ₀= hc ₀ , where ₀ is the threshold wavelength, hence ₀=9 . Hence, option (A) is correct.