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Rainbows. Waves The white light spectrum 1.White light is a mixture of different colours of light. 2.Newton used a glass prism to separate the colours.

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Presentation on theme: "Rainbows. Waves The white light spectrum 1.White light is a mixture of different colours of light. 2.Newton used a glass prism to separate the colours."— Presentation transcript:

1 Rainbows

2 Waves The white light spectrum 1.White light is a mixture of different colours of light. 2.Newton used a glass prism to separate the colours. 3.He identified 7 different colours. 4.Initials ROYGBIV

3 Waves The white light spectrum Violet is refracted more than red The prism refracts the light

4 Light Wavelengths

5 Waves The electromagnetic spectrum

6 Waves Electromagnetic waves 1.Light is a transverse wave 2.It is one part of a much bigger family 3.This family is called electromagnetic waves

7 Waves Electromagnetic waves – common features 1.Transverse 2.Can travel through empty space 3.Speed in empty space m/s ( miles per second – not hour) 4.Can be reflected, refracted, diffracted.

8 Waves Electromagnetic waves – differences Each part is made of waves with different 1.frequencies and 2.wavelengths

9 Waves Electromagnetic waves – parts 1.Radio/tv 2.Microwaves 3.Infra-red 4.Visible light 5.Ultraviolet 6.X-rays 7.Gamma - rays Long waves Low frequency Short waves High frequency

10 Waves Electromagnetic waves – parts 1.Radio/tv 2.Microwaves 3.Infra-red 4.Visible light 5.Ultraviolet 6.X-rays 7.Gamma - rays

11 Waves Electromagnetic waves – parts

12 Waves Radio-TV waves Used to transmit radio and TV programmes

13 Waves Radio-TV waves Long waves reflected by the ionosphere and can travel long distances ionosphere

14 Waves Microwave radiation - 1 Used for transmitting information to satellites

15 Waves Microwave radiation - 2 Mobile phones transmit and receive microwaves

16 Waves Microwave radiation Microwaves are absorbed by water making it hot 2.they can penetrate and cook food with a water content.

17 Action of microwaves

18 Waves Infra red radiation - 1 Can be detected by the skin as heat. Emitted by all hot objects

19 Waves Infra red radiation Used for cooking in grills and toasters 2.Used for heating in radiant type heaters

20 Waves Infra red radiation - 3 TV remote controls emit infra red

21 Waves Infra red radiation - 4 Passive infra red detector used for alarm systems

22 Waves Visible light Used for seeing – the eyes detect light

23 Waves Visible light Cameras detect light

24 Waves Visible light Air, water, glass etc let light pass through them. They are transparent.

25 Waves Ultra violet radiation - 1 Fluorescent tube light produce uv inside the tube

26 Waves Ultra violet radiation - 2 Sun beds contain uv lamps

27 Waves Ultra violet radiation - 3 UV is used in security coding – special inks glow under UV.

28 Waves X-radiation (rays) X-rays can travel through skin, muscle or flesh. 2.X-rays cannot travel through bone or metal 3.They are used to produce shadow pictures of bones and metal

29 X ray cat pin

30 Waves X-radiation (rays) - 2

31 Waves Gamma radiation (rays) -1 Gamma rays can kill harmful bacteria in food.

32 Waves Gamma radiation (rays) - 2 Gammas are used to sterilise surgical equipment

33 Waves Gamma radiation (rays) - 3 Gamma rays are used in medicine to kill cancer cells

34 Stars emit em waves Stars emit all types of em waves 1.we see the visible 2.Feel the IR 3.May be damaged by the UV 4.Astronomers look at all the parts

35 Waves The effect on living cells of microwaves 1.Absorbed by the water in cells 2.The cells can be damaged or killed by the heat

36 Waves The effect on living cells of infra red 1.Absorbed by skin 2.Felt as heat 3.Can cause burns

37 Waves The effect on living cells of ultra violet 1.Can pass through skin to deeper tissues. 2.Absorbed more by darker skin 3.High doses can kill normal cells

38 Waves The effect on living cells of X –rays and gamma rays Can pass through soft tissues Some is absorbed by the cells High doses can kill normal cells Low doses can cause normal cells to mutate and become cancerous

39 Waves Ionising radiation Gamma and X radiation are ionising and must be treated with caution. They can be both useful and dangerous.


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