The amplitude of a plane wave refers to the maximum displacement or intensity of the wave. In the context of physics, a plane wave is a type of wave that has a constant amplitude and phase over any plane perpendicular to the direction of propagation.
For a sinusoidal plane wave, such as an electromagnetic wave or sound wave, the amplitude represents the maximum displacement or variation in the wave's pressure, electric field, or any other relevant quantity. It is typically denoted by the symbol "A" and is measured in units such as meters (for displacement) or volts per meter (for electric field strength), depending on the nature of the wave.
The amplitude of a plane wave determines the wave's energy content and the perceived intensity or loudness in the case of sound waves. It plays a crucial role in various wave phenomena and calculations, such as interference, diffraction, and superposition.