Waves
Waves transfer energy from one point to another by means of vibrations.
For example:
- sound waves cause air particles to vibrate back and forth;
- ripples cause water particles to vibrate up and down.
The direction of these vibrations is the difference between A wave that moves in the same direction as the direction in which the particles are vibrating. and A wave that moves in a direction at right angles to the way in which the particles are vibrating..
Longitudinal waves
Demonstrating longitudinal waves
Longitudinal waves show areas of compression and rarefaction:
- compressions are regions of high pressure due to particles being close together.
- rarefactions are regions of low pressure due to particles being spread further apart.
Image caption, 1. An outstretched slinky spring
1 of 3
In the diagram, the compression moved from left to right and energy is transferred from left to right.
The movement of the coils of the slinky and the energy are parallel.
However, none of the particles are transported along a longitudinal wave.
Instead, they move backwards and forwards as the wave is transmitted.
Examples of longitudinal waves include:
- Sound waves.
- Ultrasound waves.
One way of remembering examples of longitudinal waves is to emphasise the O in:
- lOngitudinal
- and sOund
- and ultrasOund.