Terminology
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s = Displacement (unit = metre, m): Displacement is the position of a particle of the medium relative to its equilibrium position.
T = Period (unit = second, s): Period is the time for one complete cycle or oscillation of the medium.
φ = Phase (unit = degrees or radians): Phase is the position (with respect to time) of the oscillation taking zero disturbance as zero time. As the disturbance goes through a cycle the position in the cycle is called the phase and, since the mathematical expression for the disturbance usually involves a sine function of the time, the phase is measured in degrees or radians. A full cycle is 360° and a quarter of a cycle is 90°.
A or a = Amplitude (unit = various): Amplitude is the maximum disturbance of the medium from its equilibrium position or state.
f = Frequency (unit = hertz, Hz): Frequency is the number of waves passing any point per second or the number of oscillations of the medium per second.
λ = Wavelength (unit = metre, m): Wavelength is the distance between two points on successive wave fronts that are in phase. A Wave Front is a line joining all points that are in phase. Successive wave fronts are drawn at the same phase and waves are one wavelength apart. Waves travel perpendicular to the wave front.
I = Intensity (unit = W/m^{2} = kg/s^{3}, W·m^{−2} = kg·s^{−3}): Intensity is the energy passing through unit area (perpendicular to the area) per second.
v = Speed (unit = m/s, m·s^{−1}): Speed is the distance travelled by a wave front per second.
