"Light is an electromagnetic wave" is the principle of:

Correct answer: (d) James Clerk Maxwell

Explanation

James Clerk Maxwell showed in the 1860s, through his equations of electromagnetism, that changing electric and magnetic fields travel together as a wave. The speed he calculated for this wave matched the measured speed of light, so he concluded that light is an electromagnetic wave.

Heinrich Hertz confirmed electromagnetic waves experimentally in 1887 with radio waves. Faraday discovered electromagnetic induction, Oersted found the magnetic effect of a current, and Newton proposed the corpuscular (particle) theory of light.