Question

What is the Frequency? How is it represented? Write its S.I. unit.

Answer 1

Hint: A wave is a disturbance that travels through a medium. It carries energy from one pace to another without the actual transfer of matter. Hence, we can say that waves carry energy from one place to another without transport of matter. Wave is described by speed, frequency, and wavelength.

Complete answer:
In Physics, frequency is described as the number of waves passing a point per unit of time. That is the number of vibrations undergone per unit time by a body in periodic motion.
The frequency of a wave can be measured by counting the number of crests or troughs passing through some point in a unit of time. The higher the number of crests or troughs, the higher will be the frequency of the wave. Higher frequency means higher energy carried by the wave.

Following is the diagram representing high and low-frequency waves.

Frequency is represented by small $f$ or by a Greek letter $\nu $ (nu).
The SI unit of frequency is Hertz \[\left( {Hz} \right)\] . One hertz is defined as one wave passing through some point in one second.

Note: One hertz is one cycle per second.
Following are the other terms associated with a wave,
Wavelength is the length or distance between two consecutive crests or troughs. Its SI unit is a meter.
Wavenumber \[\left( {\overline \nu } \right)\] is the reciprocal of the wavelength.
Time period \[\left( T \right)\] is the time taken by a wave to complete one cycle and its SI unit is second. Time period and frequency are reciprocal of each other.
Amplitude is the distance from the middle of the wave to the trough or crest. The larger the amplitude of a wave, the larger its energy. Its SI unit is a meter.