# An introduction to waves

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Science An introduction to waves Light can be used for digital communications - for example, in Morse code and in CD players. Light consists of transverse waves in which the electromagnetic vibrations are at 90º to the direction of travel. The speed of a wave can be calculated using its frequency and wavelength. Lasers produce intense narrow beams of light. Transverse waves Waves are vibrations that transfer energy from place to place without matter - solid, liquid or gas - being transferred. Think of a Mexican wave in a football crowd. The wave moves around the stadium, while each spectator stays in their seat - only moving up, and then down, when it is their turn. In transverse waves, the oscillations (vibrations) are at right angles to the direction of travel and energy transfer. Water waves are transverse waves. Light and other types of electromagnetic radiation are transverse waves. All types of electromagnetic waves travel at the same speed through a vacuum, such as through space. Features of waves You should understand what is meant by the amplitude, wavelength and frequency of a wave. Amplitude As waves travel, they set up patterns of disturbance. The amplitude of a wave is its maximum disturbance from its undisturbed position. Take care: the amplitude is not the distance between the top and bottom of a wave. Amplitude and wavelength Wavelength The wavelength of a wave is the distance between a point on one wave and the same point on the next wave. It is often easiest to measure this from the crest of one wave to the crest of the next wave, but it doesn't matter where as long as it is the same point in each wave. Frequency The frequency of a wave is the number of waves produced by a source each second. It is also the number of waves that pass a certain point each second. The unit of frequency is the hertz (Hz), which is one wave per second. It is common for kilohertz (kHz), megahertz (MHz) and gigahertz (GHz) to be used when waves have very high frequencies. For…