Question

A photoelectric surface is illuminated successively by monochromatic light of wavelength λ and λ/2. If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 times that in the first case, the work function of the surface of the material is 

(h = Planck's constant, c = speed of light)

(a) 2hc/λ

(b) hc/3λ

(c) hc/2λ

(d) hc/λ

Answer 1

The correct option is (c) hc/2λ.

Explanation:

Let ϕ_o be the work function of the surface of the material. Then, According to Einstein's photoelectric equation, the maximum kinetic energy of the emitted photoelectrons in the first case is