Arrange the following electromagnetic waves in decreasing order of their wavelengths:
A. X-rays
B. Microwaves
C. Gamma rays
D. Radio waves
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → D, B, A, C
In the electromagnetic spectrum the wavelength falls steadily from radio waves to gamma rays (and the frequency rises). The usual wavelength ranges are:
(D) Radio waves: longer than about 0.1 m
(B) Microwaves: about 0.1 m down to 1 mm
(A) X-rays: about 10 nm down to \( 10^{-4} \) nm
(C) Gamma rays: shorter than about \( 10^{-3} \) nm
So the decreasing order of wavelength is D, B, A, C.
Note: A similar question was also asked in CUET (UG) 2026 on 15-05-2026 (Slot 1).
NCERT (2026-27):
Summary – “… 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 \( 10^{6} \) m.”