1. 1.To understand some common sources of waves 2.To understand the differences between longitudinal and transverse waves 3.To understand properties which are common to all waves Book Reference : Pages 174-175

2. There are many different types of waves but broadly they can be split into two types: Mechanical Waves : These require a medium to travel through : Examples include sound, water waves and seismic waves. They all require a medium for vibration to be transmitted. Electromagnetic Waves : Vibrating electromagnetic fields which are able to travel through space without the need for a medium. Examples include light, radio waves, microwaves and X-rays

3. In Longitudinal waves the direction of vibration is parallel to the direction of wave travel Direction of travel (Propagation) Examples include : Sound waves & Primary seismic waves Direction of vibration

4. In Transverse waves the direction of vibration is perpendicular to the direction of wave travel Direction of travel (Propagation) Examples include : All electromagnetic waves & Secondary seismic waves Direction of vibration

5. WaveMotion Animation

6. The displacement of a vibrating particle is its distance and direction from the equilibrium position The Amplitude is the maximum displacement. For a transverse wave this is the maximum height of the wave crest or trough. It can be thought of in terms of energy, power, volume or loudness

7. The wavelength is the distance in metres between the same point on two successive waves The top of the wave is called the crest The bottom of the wave is called the trough

8. The frequency of a wave is the number of cycles per second. Units are Hertz (Hz) The Period T, (measured in seconds) of a wave with frequency f is the time for one complete wave and is given by T = 1/f WaveMeasure Animation WaveCharacteristics Animation

9. We have seen that there is a strong relationship between wavelength and frequency. As you increase one the other reduces in proportion. There is a relationship between the two... This is the speed of the wave which is given by: Wave speed(m/s) = frequency(Hz) x wavelength (m) c = f c = f

10. With transverse waves the displacement is perpendicular to propagation.... There is still a further dimension to consider : The wave can vibrate up-down or left-right and everything in between

11. Further examples

12. Polarised sunglasses reduce reflected glare Light from the original source is likely to be unpolarised. However, annoying reflections from water and glass are likely to be polarised and can be removed with a filter