electromagnetic waves

Oscillating electric and magnetic fields travelling together through space at a speed of approximately 300,000 kps/186,000 mps. Visible light is composed of electromagnetic waves. The electromagnetic spectrum is a family of waves that includes radio waves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays. All electromagnetic waves are transverse waves. They can be reflected, refracted, diffracted, and polarized.

Radio and television waves lie at the long wavelength-low frequency end of the spectrum, with wavelengths longer than 10⁻⁴ m. Infrared radiation has wavelengths between 10⁻⁴ m and 7 × 10⁻⁷ m. Visible light has yet shorter wavelengths from 7 × 10⁻⁷ m to 4 × 10⁻⁷ m. Ultraviolet radiation is near the short wavelength-high frequency end of the spectrum, with wavelengths between 4 × 10⁻⁷ m and 10⁻⁸ m. X-rays have wavelengths from 10⁻⁸ m to 10⁻¹² m. Gamma radiation has the shortest wavelengths (less than 10⁻¹⁰ m). The different wavelengths and frequencies lend specific properties to electromagnetic waves. While visible light is diffracted by a diffraction grating, X-rays can only be diffracted by crystals. Radio waves are refracted by the atmosphere; visible light is refracted by glass or water.