Arrange the following radiations in the decreasing order of their energy
(A) Microwaves
(B) \( \gamma \)-rays
(C) AM radio waves
(D) Infrared waves
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (B), (D), (A), (C)
The photon energy of a radiation is \( E = h\nu = hc/\lambda \), so it decreases as the frequency decreases (wavelength increases). In the electromagnetic spectrum the frequency falls in the order
\( \gamma\text{-rays} \gt \text{infrared} \gt \text{microwaves} \gt \text{AM radio waves} \)
\( \gamma \)-rays have the shortest wavelengths and AM radio waves the longest. So the decreasing order of energy is B, D, A, C.
NCERT (2026-27):
Summary – “… 6. The spectrum of electromagnetic waves stretches, in principle, over an infinite range of wavelengths. Different regions are known by different names; γ-rays, X-rays, ultraviolet rays, visible rays, infrared rays, microwaves and radio waves in order of increasing wavelength from 10–2 Å or 10–12 m to 106 m.”