1. Properties of waves

2. Wave shape
peak
trough

3. 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).

4. Wave equation

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

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

7. 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)

8. Refraction

9. This causes the light to bend or refract.
Refraction
The speed of light waves depends on the material they are travelling through.
air = fastest
glass = slower
diamond = slowest
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.
glass
air

10. Refraction at the air-glass boundary

11. Refraction

12. Refraction

13. Refraction

14. 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?
In the water.
In a similar way, as light moves from one medium to another of different density, the speed of light changes.
Do you think light moves faster or slower in a more dense medium?
Light moves slower through a more dense medium.

15. 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.
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.

16. 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.
mud
road
If it enters the field at an angle then the front tyres hit the mud at different times.
tyre 2
tyre 1
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.

17. Apparent depth
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.
image
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

18. Examples of Transparent Materials
Materials and light
Examples of Transparent Materials
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.
Clear glass
Clean water
Clear plastic

19. Examples of Translucent Materials
Materials and light
Examples of Translucent Materials
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.
Thin fabrics
Frosted glass
Thin paper

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

21. Materials and light These objects will cast a shadow when lit up.
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

22. White light

23. Splitting white light into colours
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:
Richard Of York Gave Battle In Vain Y

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

25. Which colour is refracted the most?
Dispersion
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.

26. Colours of the spectrum

27. Absorption of light

28. Seeing colours How do you see non-luminous objects such as a book?
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?

29. Primary colours animation

30. Primary and secondary colours
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?
yellow
red
green
The three primary colours of light are red, green and blue.
magenta
cyan
blue
The colours made by mixing two primary colours are called
the secondary colours – magenta, yellow and cyan.

31. Which primary colours?

32. 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.

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.
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.

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

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

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

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

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

39. THE FRUIT BOWL IN WHITE LIGHT
A red apple
A green pear
A white plate

40. THE FRUIT BOWL IN RED LIGHT
A red apple
A green pear
A white plate

41. THE FRUIT BOWL IN BLUE LIGHT
A red apple
A green pear
A white plate

42. 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.

43. 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.

44. FILTERS white light – red filter

45. FILTERS white light – blue filter

46. FILTERS blue light – blue filter

47. FILTERS blue light – red filter

48. FILTERS white light – red and blue filter

49. Coloured light activity – instructions
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.

50. Coloured light activity 1
Drag and drop activity
Decide which colours the girl’s t-shirt and trousers will appear in green light and drag the clothes that show these colours onto the girl.
If correct, the clothes will stay in place; if incorrect, the clothes snap back to their original position.

51. Coloured light activity 2
Drag and drop activity
Decide which colours the girl’s t-shirt and trousers will appear in magenta light and drag the clothes that show these colours onto the girl.
If correct, the clothes will stay in place; if incorrect, the clothes snap back to their original position.

52. Flag colours in different coloured light
How would the colours in this flag appear under these lighting conditions?
red light
green light
blue light

53. What colour does it appear?
What colour does each object appear under the given lighting conditions?
Object (Colour)
Colour Filter
Appearance
red ball
red
blue
blue book
green
magenta
green apple
cyan
red and blue tie
red
black
black
blue
green
black
red and black

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

55. Light Puzzle

58. Anagrams

59. Multiple-choice quiz