1. What we will do today: Define the two forms of waves using ‘slinky’s’. Identify the following wave characteristics from a wave: wavelength, amplitude, frequency and period.

2. Types of wave There are two forms of wave movement: 1.Transverse waves 2.Longitudinal waves

3. Slinky drop in slow motion http://www.youtube.com/watch?v=r Cw5JXD18y4

4. 1. Transverse Waves Transverse waves are waves whose vibrations (energy) moves in an “up and down” motion. We say they are ‘at right angles to the wave direction’. Example of transverse waves are light, radio & TV and water waves.

5. 2. Longitudinal Waves Longitudinal waves are waves whose vibrations (energy) moves in a “back and forward” motion. We say they are ‘parallel to the wave direction’. The only example of longitudinal waves are “sound waves”. (hint: long sounds like song and singing is a sound).

6. 2003 Qu: 18

7. 2004 Qu: 16

8. 2007 Qu: 28

9. 2010 Qu: 27 (V sound = 340 m/s)

10. Wave Properties

11. Amplitude Is the height of a wave from the centre to the top or the centre to the bottom. It has the symbol A and has the unit of distance, m.

12. Wavelength Is the length of one complete wave. It has the symbol, λ, and also has the unit of distance, m.

13. Frequency Is the number of waves produced in a unit of time, usually one second. It has the symbol, f, and is measured in Hertz, Hz. It can be found by dividing number of waves by the unit of time. Eg 120 waves pass a point in one minute, what is the frequency? f = 120 / 60 = 2 Hz

14. Period Is the time taken for one complete wave to pass a certain point. It has the symbol T, and is measured in seconds, s.

15. Period & frequency Period, T (s), and frequency, f (Hz) are related by the following equation: T =1re-arrangedf =1 fTfT The above formula is not given in the data book.

16. Example f = 20 Hz T =?

17. Example The diagrams shows a side view of a water wave in a ripple tank. The vibrating bar was set at a frequency of 5 Hz: Find values for: (a) wavelength; (b) amplitude; (c) no. of waves per second; (d) Period

18. Waves Properties - Summary QuantityDefinitionSymbolUnit WavelengthLength of one full waveλm AmplitudeDistance from centre to top of wave Am FrequencyNo of waves in a unit of time fHz PeriodTime taken for one complete wave to pass Ts

19. 2005 Qu: 12

20. 2008 Qu: 12

21. 2010 Qu: 13