2. Waves Part 1 Basics

3. What is a wave? A wave is a disturbance that carries energy through matter or space

4. Waves Themes These are some of the areas of interest that involve waves 1.Sight and vision 2.Sound and hearing 3.Communications 4.Medicine 5.Cooking 6. astronomy And more…………

5. The uses of waves 1.Microwave 2.Radar 3.Mobile 4.TV 5.Radio 6.CD 7.Music 8.Satellite 1.X-rays 2.Ultrasound 3.Gamma-rays 4.Fibre optics 5.Remote control 6.….. 7.…..

6. Waves The characteristics of waves Waves are 1.Regular patterns of disturbance 2.Made by vibrations They 3.Transmit energy 4.Do not transmit matter

7. Waves The two main types Transverse (b) 1.on a rope 2.on the surface of water 3.light Longitudinal (a) 1.in a spring 2.Sound longitudinal transverse

8. When a crowd does “ the Mexican wave ” at a sporting event, they are performing as a transverse wave The wave moves in a circle around the stadium, but the people move up and down Transverse Waves Waves Transverse particle motion

9. The motion of the particles in the medium is at a right angle to the motion of the wave as a whole

10. Waves Transverse particle motion

11. Waves Longitudinal The particles move in the same direction as the wave motion

12. Waves Terms – wavelength - longitudinal Compression (C) – rarefaction (R) λ CRCRCRCRCRCR =wavelength

13. Waves Terms – wavelength - transverse Crest (C) –Trough (T) T C CC λ =wavelength

14. Waves Terms – wavelength Wavelength The distance between two consecutive Crests or troughs Compressions or rarefactions

15. Waves Terms – amplitude - longitudinal Amplitude The maximum (biggest) disturbance or displacement.

16. Waves Terms - frequency Frequency The number of waves made or passing by in 1 second Unit – Hertz (Hz)

17. Waves Terms - speed Speed The distance a wave travels in one second. start1 second later

18. Waves Symbols and units unitsymbol amplitudemA wavelengthmλ or w frequencyHzf speedm/ss,v or c!

19. Waves Formula s,v or c -speed w or λ – wavelength s fλ

20. Waves on water

21. Waves Transverse waves on water – a side view Direction of travel Particle motion – not 100% correct!

22. Waves Transverse waves on water – from above = wave motion = crest = source Waves travelling out from the source

23. Waves spreading The previous slides show waves moving along a line. Waves can spread out moving across the surface of the sea ( 2 dimensions) or through space ( 3 dimensions)

24. Waves Light and sound Light 1.Transmits energy 2.Transverse 3.Does not need a medium – can travel through empty space Sound 1.Transmits energy 2.Longitudinal 3.Needs a medium – solid – liquid - gas

25. Wave Interactions-- Reflection Reflection is what happens when a wave strikes a surface or boundary Waves reflect at a free boundary At a fixed boundary, waves reflect and turn upside down

26. Waves Reflection -sound 1.Sound is reflected when it meets a boundary between two materials – air/brick. 2.Reflected sound can produce an echo.

27. Echo - reflection

28. Waves Reflection – spring waves Waves can be reflected at the fixed end of a spring.

29. Waves Reflection - light 1.Light is reflected when it meets a boundary between two materials – air/mirror – air/paper. 2.Light reflected by a mirror produces an image.

30. Waves Reflection – light - diagrams Reflection by a plane mirror

31. Waves Reflection – water waves - diagrams Water waves are reflected by barriers

32. Waves Refraction - light When waves pass from one medium into another, they are bending due to a process called refraction This is why a spoon looks like it is broken into 2 pieces when it is resting in a glass half-full of water

33. Waves Refraction – light - diagrams There is some reflection as well.

34. Waves Refraction- water waves – diagrams -1 When water waves pass from deep water to shallow water they slow down. The wavelength decreases. deep-fastshallow-slow

35. Waves Refraction- water waves – diagrams -2 deepshallow The direction changes as well – this is refraction

36. Waves Diffraction Waves spread when they 1.pass through a gap 2.go past an obstacle

37. Waves Diffraction – narrow slit Narrow slit – more diffraction

38. Waves Diffraction – wide slit Wide slit – less diffraction

39. Waves Diffraction – past an obstacle -1 Short radio waves – less diffraction Radio transmitte r No reception

40. Waves Diffraction – past an obstacle -2 Long radio waves – more diffraction Radio transmitte r reception