# Waves: Types of Waves, Wavelength of a Wave, Time Period of Oscillation (For CBSE, ICSE, IAS, NET, NRA 2022)

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Wave, propagation of disturbances from place to place in a regular and organized way.

## Wave

• Most familiar are surface waves that travel on water, but sound, light, and the motion of subatomic particles all exhibit wavelike properties.
• In the simplest waves, the disturbance oscillates periodically with a fixed frequency and wavelength.

## Types of Waves

There are four types of waves as given below:

### Mechanical Waves

• Which can exist in material media and follows Newton՚s laws.
• A wave which needs a medium in order to propagate itself. Sound waves, waves in a Slinky, and water waves are all examples of this.

### Transverse Waves

Transverse waves are referred to those whose particles oscillate in a perpendicular motion of the direction of propagation of the wave

#### Examples of Transverse Waves

• Water waves (ripples of gravity waves, not sound through water)
• Light waves
• S-wave earthquake waves
• Stringed instruments
• Torsion wave

### Longitudinal Waves

Longitudinal waves are referred to those whose particles oscillate along the way of the propagation of the wave

#### Examples of Longitudinal Waves

• Sound waves
• P-type earthquake waves
• Compression wave

When the waves move from one point of the medium to another is called progressive wave.

## Wavelength of a Wave

• In the case of a progressive wave, the distance between two points in the same phase at that time period is known as the wavelength of a wave.
• Distance is twice the number of two consecutive nodes and antinodes.

## Time Period of Oscillation

When an element of a medium takes time to move through one complete oscillation then it is called time period.

## Principle of Superposition of Waves

• In a medium when multiple waves transverse simultaneously, the displacement is the algebraic sum of the displacements due to each wave.
• This phenomenon is referred to as the principle of superposition.

## Standing Waves

• When two identical waves moving in opposite directions interfere, it results in a standing wave.
• These waves are characterized by the zero displacement locations which are fixed and are called as nodes and locations of maximum displacements called as antinodes.

## Doppler Effect

• Change in the frequency of a wave when the source or the observer or both are moving relative to the medium.
• So, this phenomenon is used in different scientific aspects such as planetary science wherein astronomers depend on this effect to identify planets exterior to the solar system.
• This Effect is an increase (or decrease) in the frequency of sound, light, or other waves as the source and observer move towards (or away from) each other.

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