Properties & Uses of Electromagnetic Waves

How electromagnetic waves are produced

• (HT) Radio waves can be produced by oscillations in electrical circuits: an alternating current in a transmitting aerial produces radio waves of the same frequency as the current
• (HT) When radio waves are absorbed by a receiving aerial they create an alternating current with the same frequency as the wave, so radio waves can themselves induce oscillations in an electrical circuit
• Changes in atoms and the nuclei of atoms can result in electromagnetic waves being generated or absorbed over a wide frequency range. Gamma rays originate from changes in the nucleus of an atom; visible light and X-rays come from changes in the electrons