Electromagnetic Wave
Electromagnetic Wave are waves composed of undulating electrical fields and magnetic fields. The different kinds of electromagnetic waves, such as light and radio waves, form the electromagnetic spectrum. All electromagnetic waves have the same speed in a vacuum, a speed expressed by the letter c (the speed of light) and equal to about 186,000 miles (or 300,000 kilometers) per second. Electromagnetic Wave transport energy, due to oscillating electric and magnetic fields, Electromagnetic Waves are called electromagnetic radiation, light, or photons.
Maxwell‘s equations predicts the existence of electromagnetic waves that travel with speed of light c =1/ μ ? . The reason is due to the fact that a changing electric field produces a magnetic field and vice versa, and the coupling between the two fields leads to the generation of electromagnetic waves.
Four Maxwell equations are:-
In 1887, Heinrich Hertz generated and detected electromagnetic waves in his lab. The waves radiated from a transmitter circuit and were detected in a receiver circuit. Hertz used the fact that electrical circuits have resonant frequencies just like mechanical systems do.
A stationary charge produces an electric field.
A charge moving at constant speed produces electric and magnetic fields.
A charge that is accelerated will produce variable electric and magnetic fields. These are electromagnetic waves.