Physics: Chapter 11 - Waves

11.1 Describing Waves
The source of a wave is vibration or oscillation.
Waves transfer energy from one point to another.
In waves, energy is transferred without the medium moving/ being transferred.

Transverse waves are waves that travel in a direction perpendicular to the direction of vibration of the particles.
Examples of transverse waves: Light waves

Longitudinal waves are waves that travel in a direction parallel to the direction of vibration of particles.

Examples of longitudinal waves: Sound waves.

11.2 Properties of Wave Motion


Crest and troughs: Highest and lowest points of a transverse waves.
Compression and rarefaction : Highest and lowest points of a longitudinal waves.

Phase: Points of a wave which move in the same direction, have the same speed and the same displacement from the original position.

Wavelength λ: Shortest distance between any two points in a wave that are in phase.
SI Unit: metre (m)

Amplitude A: Maximum distance from the rest position. It is the height of a crest or depth of a trough.
SI Unit: metre (m)


Period (T): Time taken for one point on the wave to complete one oscillation.
SI Unit: second (s)

Frequency (f): Number of complete waves produced per second.
SI Unit: Hertz (Hz)
f = 1/T

Wave speed (v): v = fλ
Wave speed = wavelength(period)
SI Unit: metre per second (m s^-1)

Wavefront: Imaginary line on a wave that joins all points that are in the same phase.