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)

hc/ 2λ

hc/λ

2 hc/λ

hc/3λ

Solution

hc/ 2λ

According to Einstein photoelectric equation,
E = K_max + Φ
Where K_max is the maximum kinetic energy of emitted electron and Φ is work function of electrons.
K_max = E - Φ = hv - Φ
K_max = $hc over straight lambda minus ϕ$
Similarly, in the second case, maximum kinetic energy of emitted electron is 3 times that in the first case, we get
3K_max $hc over straight lambda minus ϕ$
solving EQs (i) and (ii), we get work function of an emitted electron from a metal surface.
Φ = hc/2λ

For Daily Free Study Material Join wiredfaculty

Wave Optics

Some More Questions From Wave Optics Chapter

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

Phone Number

Email Address

Location