Columbia Encyclopedia

Search results

321 results found

waveguide

(Encyclopedia)waveguide, device that controls the propagation of an electromagnetic wave so that the wave is forced to follow a path defined by the physical structure of the guide. Waveguides, which are useful chie...

bore

(Encyclopedia)bore, inrush of water that advances upstream with a wavelike front, caused by the progress of incoming tide from a wide-mouthed bay into its narrower portion. The tidal movement tends to be retarded b...

electrocardiography

(Encyclopedia)electrocardiography ĭlĕkˌtrōkärdēŏgˈrəfē [key], science of recording and interpreting the electrical activity that precedes and is a measure of the action of heart muscles. Since 1887, when ...

frequency

(Encyclopedia)frequency: see harmonic motion; wave. ...

surf

(Encyclopedia)surf: see wave, in oceanography; beach. ...

period, in physics

(Encyclopedia)period, in physics: see harmonic motion; wave. ...

modulation, in communications

(Encyclopedia)CE5 Modulation modulation, in communications, process in which some characteristic of a wave (the carrier wave) is made to vary in accordance with an information-bearing signal wave (the modulatin...

amplitude

(Encyclopedia)amplitude ămˈplĭto͞odˌ [key], in physics, maximum displacement from a zero value or rest position. In the harmonic motion of a pendulum, the amplitude of the swing is the greatest distance reache...

oscillator, electronic

(Encyclopedia)oscillator, electronic ŏsˈəlāˌtər [key], electronic circuit that produces an output signal of a specific frequency. An oscillator generally consists of an amplifier having part of its output ret...

sound

(Encyclopedia)CE5 Sound waves: An air pressure wave radiating outward from a loudspeaker is perceived as sound. sound, any disturbance that travels through an elastic medium such as air, ground, or water to be ...