Amplituud

Amplituud is a measure of the extent of displacement or strength of a vibrating object or periodic signal from its rest position. It indicates how large the oscillation or wave is and is defined as the maximum deviation from equilibrium for the quantity being measured.

For a simple harmonic motion or sinusoidal signal, the amplitude A equals the peak value of the quantity (displacement, voltage, pressure, etc.). The peak-to-peak amplitude is 2A. The root-mean-square (RMS) value, often used for power considerations, is A divided by the square root of 2 for a pure sine wave.

In waves and acoustics, amplitude relates to the height of the wave and to the pressure variation in sound waves. Larger amplitudes generally correspond to higher intensities and, roughly, to louder sounds, though perceived loudness depends on human sensitivity and frequency.

In optics and electromagnetism, amplitude describes the strength of the wave’s electric or magnetic field. The light or signal’s intensity is proportional to the square of its amplitude. Measurement of amplitude depends on the context and medium, and can be expressed in units such as meters for displacement, volts for electrical signals, or pascals for sound pressure.

Etymology: amplitude derives from the Latin word amplitude, meaning breadth or extent. Related concepts include peak amplitude, RMS amplitude, and amplitude modulation.