Class 12 Physics
CBSE and UP Board
Dual Nature of Radiation and Matter
Chapter-11 Exercise 11.9
NCERT Solutions for Class 12 Physics Chapter 11 Question-9
The work function for a certain metal is 4.2 eV. Will this metal give photoelectric emission for incident radiation of wavelength 330 nm?
Share
No
Work function of the metal, φO = 4.2 eV
Charge on an electron, e = 1.6 x 10-19 C
Planck’s constant, h = 6.626 x 10–34 Js
Wavelength of the incident radiation, λ = 330 nm = 330 x 10⁻9 m
Speed of light, c = 3 x 108 m/s
The energy of the incident photon is given as:
E = hc/λ = (6.626 x 10–34) x ( 3 x 108) /(330 x 10⁻9)
=6.0 x 10⁻19J
=(6.0 x 10⁻19J)/(1.6 x 10⁻19 ) = 3.76 eV
It can be observed that the energy of the incident radiation is less than the work function of the metal. Hence, no photoelectric emission will take place.