EM Waves & LASER — A/L Physics

Electromagnetic (EM) Wave A transverse wave consisting of mutually perpendicular oscillating electric (E) and magnetic (B) fields, propagating through space without a medium. The fields are in phase, perpendicular to each other and to the direction of propagation. EM waves travel at speed c = 3.00 × 10⁸ m/s in vacuum. Examples include radio waves, light, and X-rays.

Electromagnetic Spectrum The continuous range of EM waves ordered by frequency or wavelength. From low frequency to high: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays. All obey c = fλ . Visible light is a tiny portion (400–700 nm). Higher frequency means higher photon energy ( E = hf ).

Properties of EM Waves All EM waves exhibit reflection, refraction, diffraction, interference, and polarization. They transfer energy and momentum. Unlike mechanical waves, they do not require a medium. Polarization (restricting E-field to one plane) is unique to transverse waves and is used in sunglasses and 3D movies.