Which of the following statements are true about electromagnetic wave…

The correct answer is Option (2) → (A), (B) and (C) only

(A) Accelerated charges radiate electromagnetic waves. — Correct. An accelerated charge produces a changing electric field, which produces a changing magnetic field, and so on; this is the source of electromagnetic waves.

(B) The frequency of the electromagnetic wave equals the frequency of oscillation of the charge. — Correct. A charge oscillating with frequency \( \nu \) produces fields that oscillate with the same frequency, so the wave has frequency \( \nu \).

(C) No material medium is involved in the vibrations of the electric and magnetic fields. — Correct. The oscillating quantities are the fields themselves, so electromagnetic waves travel even through vacuum.

(D) Electromagnetic waves of different wavelengths have different velocities in free space/vacuum. — Incorrect. In vacuum all electromagnetic waves travel with the same speed \( c \), whatever their wavelength.

    \( \displaystyle c = \frac{1}{\sqrt{\mu_0\varepsilon_0}} = 3\times10^{8}\,\mathrm{m\,s^{-1}} \)

NCERT (2026-27):
Sources of Electromagnetic Waves – “… It is an important result of Maxwell’s theory that accelerated charges radiate electromagnetic waves. … The frequency of the electromagnetic wave naturally equals the frequency of oscillation of the charge.”

Nature of Electromagnetic Waves – “… They differ from all the other waves we have studied so far, in respect that no material medium is involved in the vibrations of the electric and magnetic fields.”

Summary – “… Electromagnetic waves other than light also have the same velocity c in free space.”