Waves are vibrations that transfer energy without any matter (solid, liquid or gas) being transferred.
e.g. light and sound travel as waves.

Waves have the following components:

• Amplitude
• Wavelength
• Time period
• Frequency

Amplitude (A) is the maximum displacement moved by a point on a wave from its equilibrium position. It is measured in metres (m).

Wavelength (λ) is the distance between two successive crests or troughs of a wave. It is measured in metres (m).

Time period (T) is the time taken for one complete cycle of vibration to pass in a given point. It is measured in seconds (s).

Frequency (ƒ) is the number of waves that pass a fixed point in a given amount of time. It is measured in Hertz (Hz). Relationship between Frequency (ƒ) and Time period (T):

• T = ¹⁄ƒ
• ƒ = ¹⁄T

In the above wave diagram,
T = 4 seconds
ƒ = ¹⁄₄ = 0.25 Hz

### Types of Waves

There are two types of waves.

Transverse Waves
In transverse waves, the vibrations are at right angles to the direction of travel of wave.
e.g. Light and other electromagnetic radiation

Longitudinal Waves
In longitudinal waves, the vibrations are parallel to the direction of travel of wave.
e.g. Sound waves

### Wave Speed

The speed of a wave is related to its frequency and wavelength. It is measured in (m/s).

Wave speed = Frequency x Wavelength
v = ƒ x λ

e.g. A wave of frequency 2000 Hz has a wavelength of 2 m. Calculate its speed.
v = 2000 x 2 = 4000 m/s