# Speed of a Wave Motion

## Speed of a Wave Motion

The speed of a mechanical wave, is clearly expected to depend upon the properties of the medium through which the wave is travelling. The medium could be a solid, liquid or a gas. All the media are characterized by their physical properties, like mass, density, elasticity and temperature.

Waves are a disturbance which moves through space. Mechanical waves such as waves which propagate through water need a medium (the water) for them to exist. Electromagnetic radiation waves such as light and radio waves do not need a medium and can travel through a vacuum.

To understand the concept of wave motion, we need to know about the three basic properties of waves.

Wavelength:

Wavelength is denoted by λ. It it’s the distance between two consecutive crest and trough. Wavelength is measured in metres (m).

Amplitude:

The amplitude (y) for the wave is given by the distance from the centre line to the top of the crest or the tip of a trough, the amplitude of the wave tells about the energy of the wave and amplitude is measured in metres (m).

Frequency:

Frequency is denoted by the symbol f and it is the number of waves passing through a point in one second and it is measured in hertz (Hz).

Speed of a wave is measured in metres per second. The speed of light is 3 x 10⁸ m/ sec.

Waves are categorised based on the way they propagate:

Transverse Waves:

Waves in which the particles in their medium move at right angles to the direction of wave motion.

Longitudinal Waves:

Waves in which particles move in the direction of wave propagation.

Spring of waves on string depends upon the tension and mass density of the string and is given by:

Speed of a Wave (v) = √(T/μ).

From the above relation, we can say that wave speed on a stretched depends on the tension in the string and the linear density of the string and not on the frequency of the wave.