Arrange the momenta of the photons of the following electromagnetic radiations in increasing order.
A. Microwaves
B. Ultraviolet rays
C. γ-rays
D. Infrared rays
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A, D, B, C
A photon of wavelength \( \lambda \) and frequency \( \nu \) carries momentum
\( \displaystyle p = \frac{h}{\lambda} = \frac{h\nu}{c} \)
So the momentum increases with frequency. Arranging the radiations by increasing frequency:
\( \text{Microwaves (A)} \lt \text{Infrared (D)} \lt \text{Ultraviolet (B)} \lt \gamma\text{-rays (C)} \)
The increasing order of momentum is A, D, B, C.