Arrange the following electromagnetic radiations in the order of incr…

The correct answer is Option (4) → D, B, A, C

The energy of a photon is \( E=h\nu \). Written with the wavelength, it is \( E=hc/\lambda \). So a shorter wavelength means a higher frequency and a larger energy per photon. Within the visible band, violet and blue lie at the short-wavelength end and red at the long-wavelength end.

(D) Radio waves — Longest wavelength of the four, so the lowest frequency and the least energy per photon; it comes first.

(B) Yellow light — Visible light has a much shorter wavelength than radio waves. Yellow lies nearer the red end than blue, so it comes second.

(A) Blue light — Shorter wavelength than yellow, so each photon carries more energy than a yellow one; it comes third.

(C) X-rays — Far shorter wavelength than visible light, so the highest energy per photon of the four; it comes last.

NCERT (2026-27):
Particle Nature of Light: the Photon – “(iii) All photons of light of a particular frequency ν, or wavelength λ, have the same energy E (=hν = hc/λ) and momentum p (= hν/c = h/λ), whatever the intensity of radiation may be. …”

Summary – “… 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.”