Accelerated charged particles produce electromagnetic waves.
Characteristics of electromagnetic waves:
(i) Electromagnetic waves are transverse in nature.
(ii) All electromagnetic waves travel through vacuum with a speed $3\times {10}^8\mathrm{m}∕\mathrm{}\mathit{s}$.
(iii) In electromagnetic waves the oscillations of $\overrightarrow{\mathit{E}}$ and $\overrightarrow{\mathit{B}}$ are perpendicular to each other and also perpendicular to the direction of propagation of the wave.