Wave Motion

A wave

A disturbance that propagates through space with the transference of energy

Mechanical waves

Need a substance called a medium in which to travel. The wave is a series of vibrations passing from molecule to molecule in the medium. (E.g. water waves, sound waves, waves on a rope, waves on a spring)

Electromagnetic waves

Do not need a medium in which to travel. They travel through a vacuum at the speed of light.

(EM spectrum is as follows: Radio waves, Microwaves, infa-red, visible light, ultraviolet, X-rays, and gamma rays)

A travelling wave

Either mechanical or electromagnetic, travels from the source producing it, transferring energy to all places through which it passes.

Reflection (wave)

The bouncing of waves off obstacles in their path

Refraction

Occurs when waves change direction as they enter a new medium

Coherent sources

Are sources which are in phase and have the same frequency

Interference

The addition of waves from more than one coherent source

An interference pattern

Is formed when two or more coherent sources meet

Constructive interference

Occurs when waves from two sources meet and the amplitude of the resultant wave is greater than the amplitude of the individual waves

Destructive interference

Occurs when waves from two sources meet and the amplitude of the resultant wave is less than the larger amplitude of the individual waves.

Diffraction (waves)

The sideways spreading of waves into a region beyond a gap or around an obstacle

Polarisation

Of waves occurs when the vibrations are confined to one plane only

A stationary or standing wave

Is formed when two waves of equal amplitude and frequency, moving in opposite directions meet.

Nodes

Are points on a stationary wave that remain at rest

Antinodes

Are points on a stationary wave that vibrate with maximum amplitude

Doppler effect

The apparent change in frequency of a wave due to the relative motion of the source and observer