Complete vibration: If a wave transmitting particle moves from a certain point and again comes back to the same point then the motion is called complete vibration.

Time period: The time interval in which the wave is repeated that is the times required for one complete vibration of a wave transmitting particle is known as its time period. It is expressed by the letter T and its unit is second (s).

Frequency: The number of complete vibrations in one second of a wave transmitting particle is known as its frequency. Wave is produced from a vibrating object. So the frequency of vibrating object is equal to the frequency of the wave. The unit of frequency is Hertz (Hz). If a vibrating particle executes one complete vibration in one second then its frequency is called 1 Hz. It is expressed by ‘f’. The relation between frequency and time period is f = 1/T

Amplitude: To produce a wave the particles need to vibrate about their equilibrium position. The maximum displacement of a wave transmitting particle from the position of equilibrium is called amplitude. In the figure ‘a’ is amplitude.

Phase: The overall condition of motion of a wave transmitting particle at any moment is known as phase. The overall condition means the displacement, velocity and acceleration etc of the particle at a certain time. The wave crest or the wave trough always remains in the same phase in case of a transverse wave.

In the figure the particles of points P and P’ or R and R’ are in same phase.

Wavelength: The distance between the two successive particles of same phase is called wave length. Wave length is defined as the distance through which a wave travels in a time during which a wave transmitting particle completes one oscillation. Wave length is expressed by γ. Its unit is meter (m). In the figure the distance PP’ or RR or SS’ is wavelength, γ.

Wave velocity: The distance that a wave travels in one second in a particular direction is called wave velocity.