### Wave

It is a disturbance produced in a medium which passes through the medium without changing its shape and size.

### Types of Wave

There are 2 types of waves:
1. Mechanical waves: These require a medium for propagation. These waves can not travel in the absence if medium. Eg: Sound Wave
2. Non-mechanical Waves. These waves do not require any medium for propagation.These waves can also travel in vacuum and space. Eg: Radio Waves

## Types of Mechanical Waves

Transverse Waves
• In transverse waves, particle vibrates perpendicular to the direction of the wave.
• Transverse waves travel in form of crest and trough.
• Transverse waves can propagate only in solid mediums and only on the surface of liquid.
• They can not travel inside a liquid on inside a gaseous medium.

Longitudinal Waves
• In Longitudinal Waves, particles vibrate along the direction of propagation of the wave.
• Longitudinal Waves travel in the form of compression and rarefaction.
• The density and pressure of the medium are maximum at the compression as the particles come closer to each other and minimum at the rarefaction as the particles move away from each other.
• Longitudinal Waves can be produced in all the 3 mediums.

## Characteristics of a Wave

Amplitude
Amplitude is the maximum displacement of the vibrating particle from the mean position. It is denoted by 'a'.

Time Period
The time period is the time taken to complete one vibration/ oscillation or time taken to complete 2 consecutive compressions or 2 consecutive rarefactions. It is denoted by 't' and its SI unit is second.

Frequency
Frequency is the number of vibrations or oscillations in one second. It is denoted by 'nuu'. Its SI unit is Hertz or Hz

Wave Length
Wavelength is the distance between 2 consecutive compressions and rarefaction. It is denoted by λ (lambda) and its SI unit is metres.