2. Properties of waves

3. Wave shape peak trough

4. Wave key words Wave key words: Wavelength – length of one complete wave, measured in metres (m). It is usually taken from the top of one peak to the top of the peak on the next wave. Amplitude – the height of the wave, usually taken from an imaginary line drawn directly through the middle of the waves, up to the peak. The bigger the amplitude, the greater the amount of energy a wave will have. Peak – the highest point of a wave. Trough – the lowest point of a wave. Frequency – the total number of complete waves that pass a given point, every second. It is measured in hertz (Hz).

5. Wave equation

6. A plane mirror reflects light regularly so that it produces a clear image which is the same size as the object. When something is reflected in a plane mirror, left becomes right and right becomes left. This is called lateral inversion. Reflection - Lateral inversion What is different about the image?

7. Reflection Circle the correct ray: A, B or C. A B C Label the ray diagram to show the following: Angle of Incidence Angle of Reflection Normal Mirror

8. Reflection summary 1. Pale and shiny surfaces are good reflectors, dark and rough surfaces are not. 2. The image in a plane mirror is laterally inverted. 3. The image is the same distance behind the mirror as the object is in front. 4. The image in a plane mirror is the same size as the object. 5. The law of reflection is: angle of incidence (i) = angle of reflection (r)

9. Refraction

10. glass air The speed of light waves depends on the material they are travelling through. air = fastestdiamond = slowestglass = slower If light waves enter a different material (e.g. travel from glass into air) the speed changes. This causes the light to bend or refract. Refraction

11. Refraction at the air-glass boundary

12. Refraction

15. In the water. Light moves slower through a more dense medium. Travelling through different materials If you were running along a beach and then ran into the water when would you be moving slower – in the water or on the sand? Do you think light moves faster or slower in a more dense medium? In a similar way, as light moves from one medium to another of different density, the speed of light changes.

16. From this bar chart, which material do you think is denser, Perspex or water? Perspex must be denser than water because light travels more slowly through Perspex than water. The speed of light in different media Light travels at 300,000 km/s in a vacuum. As light enters denser media, the speed of light decreases.

17. mud road Why does light change direction? Imagine a car driving from the road into a muddy field. In the muddy field it slows down as there is more friction. If it enters the field at an angle then the front tyres hit the mud at different times. Tyre 1 hits the mud first and will move more slowly than tyre 2. This causes the car to turn towards the normal. When the car leaves the mud for the road, tyre 1 hits the road before tyre 2 and this causes the car to turn away from the normal. tyre 1 tyre 2

18. The rays of light from a stone get bent (refracted) as they leave the water. Your brain assumes these rays of light have travelled in straight lines. Your brain forms an image at the place where it thinks the rays have come from – the stone appears to be higher than it really is. actual location image Apparent depth

19. Materials and light Transparent Light Materials that you can see through allow almost all of the light to pass through. Light is allowed through with very little bending or scattering of the rays of light. Examples of Transparent Materials Clear glass Clean water Clear plastic

20. Materials and light Translucent Light Materials that allow only some light to pass through. Objects allow light to pass through, but they scatter the rays so much that you cannot get a clear view of what is on the other side. Examples of Translucent Materials Thin fabrics Frosted glass Thin paper

21. Materials and light Opaque Light Light cannot pass through these materials. Examples of Opaque Materials Brick Metal Thick paper Aluminum Foil Wood Stones

22. Materials and light Quick Facts about Opaque Materials These objects will cast a shadow when lit up. Brick, metal, and thick paper stop light completely. We say the light has been absorbed. Ray of light Opaque brick wall absorbs all the light No light is transmitted through the wall

23. White light

24. A prism splits a ray of white light into a spectrum of colours. This is known as dispersion. When white light is split, the colours always follow the same order. Use this phrase to remember the order of colours: Splitting white light into colours Richard Of York Gave Battle In Vain

25. Each of the colours of the spectrum [ROYGBIV] has a slightly different wave. What is the difference? Each colour has a different wavelength ( ). Dispersion

26. The different colours of light have different wavelengths, this means they are bent (refracted) by different amounts. Which colour is refracted the most? Red light is refracted least because it has the longest wavelength. Violet light is refracted the most because it has the shortest wavelength. Dispersion

27. Colours of the spectrum

28. Absorption of light

29. You see a non-luminous object when light hits the object and is then reflected into your eyes. So how do we see different colours? Why does a red dress look red? Why does a green apple look green? How do you see non-luminous objects such as a book? Seeing colours

30. Primary colours animation

31. Colours are made by mixing other colours of light. There are three primary colours of light used to make all other colours. What are these colours? red green blue The three primary colours of light are red, green and blue. magenta Primary and secondary colours The colours made by mixing two primary colours are called the secondary colours – magenta, yellow and cyan.

32. Which primary colours?

33. Coloured objects in white light Reflection and absorption of light Opaque objects reflect and absorb light. The color of an opaque object is the color it reflects. It absorbs all the other colours. This apple reflects red and absorbs all other colours.

34. Coloured objects in white light Reflection and absorption of light Opaque objects reflect and absorb light. The color of an opaque object is the color it reflects. It absorbs all the other colours. The red pepper reflects red light and absorbs all the other colours. The green pepper reflects green light and absorbs all the other colours. The yellow pepper reflects yellow light and absorbs all the other colours.

35. COLOURED OBJECTS White object in white light  All colours reflected White objects reflect all colours and absorb none Object appears white

36. OBJECTS IN COLOURED LIGHT White object in blue light  Blue light reflected White objects reflect all colours and absorb none Object appears blue

37. OBJECTS IN COLOURED LIGHT White object in red light  Red light is reflected White objects reflect all colours and absorb none Object appears Red

38. OBJECTS IN COLOURED LIGHT Red object in red light  Red is reflected Red Objects reflect red light Object appears Red

39. OBJECTS IN COLOURED LIGHT Red object in blue light  No light is reflected Red Objects reflect red light and absorb all others Object appears black

40. A red appleA green pear A white plate THE FRUIT BOWL IN WHITE LIGHT

41. A red appleA green pear A white plate THE FRUIT BOWL IN RED LIGHT

42. A red appleA green pear A white plate THE FRUIT BOWL IN BLUE LIGHT

43. Coloured filters in white light A coloured filter will allow it’s colour to be transmitted through the filter, while absorbing all the other colours of white light.

44. Coloured filters in coloured light A coloured filter will allow it’s colour to be transmitted through the filter, while absorbing all the other colours of white light.

45. FILTERS white light – red filter

46. FILTERS white light – blue filter

47. FILTERS blue light – blue filter

48. FILTERS blue light – red filter

49. FILTERS white light – red and blue filter

50. The next two slides include a girl wearing a t-shirt and trousers. The girl is standing in a different coloured light each time. The colour of this light is written at the top of the slide. The aim of each activity is to decide what colours the girls’ clothes would appear in each type of coloured light. Drag the correct t-shirt and trousers onto the girl to find out if you have selected the correct colours. Coloured light activity – instructions

51. Coloured light activity 1

52. Coloured light activity 2

53. How would the colours in this flag appear under these lighting conditions? Flag colours in different coloured light a)red light b)green light c)blue light

54. Object (Colour)Colour FilterAppearance red ballred red ballblue blue bookgreen blue bookmagenta green applecyan green applemagenta red and blue tiered black blue green black red and black What colour does each object appear under the given lighting conditions? What colour does it appear?

55. Sound Word Search Find the eight sound related words and match them to their meanings. One has been done for you.

56. Light Puzzle

59. Anagrams

60. Multiple-choice quiz