Of the following, the correct arrangement of electromagnetic spectrum in decreasing order of wavelength is ________________.
Fill in the blank with the correct answer from the options given below.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Radio waves, microwaves, Infrared waves, visible waves, X-rays
In the electromagnetic spectrum the wavelength decreases (and the frequency increases) from radio waves to gamma rays. Typical wavelength ranges:
\( \text{Radio waves: } \gt 0.1\,\mathrm{m} \)
\( \text{Microwaves: } 0.1\,\mathrm{m} \text{ to } 1\,\mathrm{mm} \)
\( \text{Infrared: } 1\,\mathrm{mm} \text{ to } 700\,\mathrm{nm} \)
\( \text{Visible: } 700\,\mathrm{nm} \text{ to } 400\,\mathrm{nm} \)
\( \text{X-rays: } 10\,\mathrm{nm} \text{ to } 10^{-3}\,\mathrm{nm} \)
So the decreasing order is radio waves, microwaves, infrared waves, visible waves, X-rays.
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 106 m.”