1. Waves Waves can transfer energy and information without a net motion of the medium through which they travel. They involve vibrations (oscillations) of some sort.

2. Rays Rays highlight the direction of energy transfer.

3. Transverse waves The oscillations are perpendicular to the direction of energy transfer. Direction of energy transfer oscillation peak trough

4. Transverse waves Water ripples Light On a rope/slinky Earthquake

5. Longitudinal waves The oscillations are parallel to the direction of energy transfer. Direction of energy transfer oscillation

6. Longitudianl waves compression rarefraction

7. Longitudinal waves Sound Slinky Earthquake

8. Amplitude - A The maximum displacement from the mean position. amplitude

9. Period - T The time taken (in seconds) for one complete oscillation. It is also the time taken for a complete wave to pass a given point. One complete wave

10. Frequency - f The number of oscillations in one second. Measured in Hertz. 50 Hz = 50 vibrations/waves/oscillations in one second.

11. Period and frequency Period and frequency are reciprocals of each other f = 1/TT = 1/f

12. Wavelength - λ The length of one complete wave. wavelength

13. Wave speed - v The speed at which the wave fronts pass a stationary observer. 330 m.s -1 YouTube - Bill Nye the Science Guy - 51: Waves 1/3

14. The Wave Equation v = fλ v λ f x

15. Electromagnetic spectrum Long Wavelength Short Wavelength Low Frequency High Frequency

16. What do they all have in common? They can travel in a vacuum They travel at 3 x 10 8 m.s -1 in a vacuum (the speed of light) They are transverse They are electromagnetic waves (electric and magnetic fields at right angles to each oscillating perpendicularly to the direction of energy transfer)

17. Reflection Incident ray Normal Reflected ray Angle of incidence Angle of reflection Mirror Angle of incidence = Angle of reflection

18. Image in a mirror Upright Same size as object Distance from mirror to object = “distance” from image to mirror Laterally inverted (?) Virtual (can’t be shown on a screen)

19. Why? “virtual” image

20. Refraction Glass block Beam of light Light going from air to glass bends towards the normal Light going from glass to air bends away from the normal Can you copy this please? CAREFULLY!!!

21. Refraction When a wave changes speed (normally when entering another medium) it may refract (change direction) Ripple Tank Simulation

22. Snell’s law i r In the case of light only, this quantity is called the refractive index (η) η = sin(i) sin(r)

23. Refraction – a few notes The wavelength changes, the speed changes, but the frequency stays the same Ripple Tank Simulation

24. Critical Angle The Critical angle is the angle of incidence that produces an angle of refraction of 90º Copy! 90º Critical angle

25. Total Internal Reflection Critical angle sin c = 1/η sin(critical angle) = 1/(refractive index)

26. Examples of Total Internal Reflection

32. Diffraction Waves spread as they pass an obstacle or through an opening

33. Diffraction Diffraction is most when the opening or obstacle is similar in size to the wavelength of the wave

34. Diffraction Diffraction is most when the opening or obstacle is similar in size to the wavelength of the wave

35. 10 4 10 3 10 2 10 1 10 0 10 -1 10 -2 10 -3 15 2525 2424 23232 2121 2020 2 -1 2 -2 2 -3 1111

36. Analogue signals are signals that vary CONTINUOUSLY Digital signals are a coded form of signal that takes the discrete values of 0 or 1 only. 0 1

37. 7 9 11 12 13 14 15

38. 70111 91001 111011 121100 131101 141110 1110 151111 1111 1111

39. 01111001101111001101111011101 111 70111 91001 111011 121100 131101 141110 1110 151111 1111 1111

40. Advantages of digital signals Less affected by interference Interference is not increased when the signal is amplified Uses weaker signals than analogue.

41. Range of hearing Humans can hear up to a frequency of around 20 000 Hz (20 kHz) Can you copy this too please?

42. Sound travels as Longitudinal waves The oscillations are parallel to the direction of energy transfer. Direction of energy transfer oscillation

43. Longitudinal waves compression rarefaction

44. Amplitude = volume Can you copy this CAREFULLY please?

45. Pitch = frequency Can you copy this CAREFULLY too please?

46. The Cathode Ray Oscilloscope YouTube - NUCLEAR PHYSICS PART 1 THE DISCOVERY OF RADIOACTIVITYYouTube - NUCLEAR PHYSICS PART 1 THE DISCOVERY OF RADIOACTIVITY Can you stick the sheets in?