Presentation is loading. Please wait.

Presentation is loading. Please wait.

© Boardworks Ltd 2004 1 of 20 © Boardworks Ltd 2005 1 of 30 KS4 Physics Dispersion and Electromagnetic Radiation.

Similar presentations


Presentation on theme: "© Boardworks Ltd 2004 1 of 20 © Boardworks Ltd 2005 1 of 30 KS4 Physics Dispersion and Electromagnetic Radiation."— Presentation transcript:

1 © Boardworks Ltd of 20 © Boardworks Ltd of 30 KS4 Physics Dispersion and Electromagnetic Radiation

2 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Dispersion and Electromagnetic Radiation Contents Explaining dispersion The electromagnetic spectrum Summary activities Uses and dangers of EM radiation

3 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Take care! The ray box will get very hot. Dispersion experiment 1. Connect a ray box to a power source. 2. Place a prism on a piece of plain paper. 3. Draw around the prism. 4. Shine a ray of light at the prism. 5. Draw in rays of light to show your observations.

4 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Explaining dispersion The white light ray is split into a spectrum of colours. This is known as dispersion. The different colours of light have different wavelengths. Different wavelengths are refracted different amounts. Red light is refracted least. Violet light is refracted the most. Which colour is refracted the most? How do you remember the order of the colours? Richard Of York Gave Battle In Vain

5 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Dispersion summary Red/violet Refracted more/less by glass Longer/shorter wavelength Red/violet Refracted more/less by glass Longer/shorter wavelength

6 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Dispersion and Electromagnetic Radiation Contents Explaining dispersion The electromagnetic spectrum Summary activities Uses and dangers of EM radiation

7 © Boardworks Ltd of 20 © Boardworks Ltd of 30 The electromagnetic spectrum Light, a type of radiation, is part of the electromagnetic spectrum. The electromagnetic spectrum is made up of different types of radiation. The different types of radiation have different properties and behaviour. All electromagnetic waves can travel through space. All electromagnetic waves travel at the same speed in a vacuum (300,000,000 m/s). TRUE/FALSE

8 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Colour, wavelength and amplitude We can see the relationship between colour, wavelength and amplitude using this activity.

9 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Although all EM waves travel at the same speed, their wavelength ( ) and frequency (ƒ) can be different. The properties, dangers and uses of EM waves depends on the wavelength ( ). Waves that cook food. Waves that cause sun-tans. Electromagnetic spectrum

10 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Radio Micro Infra- Red Light Ultra- Violet X rays Gamma Wavelength ( ) increases Can you think of a phrase that would help you remember this order? Gate X Usually Lets In Most Radiation High frequency Short wavelength High energy Most penetrating Low frequency Long wavelength Low energy Least penetrating Electromagnetic spectrum

11 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Electromagnetic spectrum

12 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Dispersion and Electromagnetic Radiation Contents Explaining dispersion The electromagnetic spectrum Summary activities Uses and dangers of EM radiation

13 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Uses and dangers of EM radiation Research the uses and dangers of the various radiations: RadiationUsesDangers Gamma X-rays Ultraviolet Light Infra red Microwaves Radio waves

14 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Killing harmful bacteria in food, sterilizing surgical equipment, killing cancer cells. High doses can kill cells. Lower doses can cause cells to become cancerous. Gamma EM radiation: Uses: Dangers: Gamma radiation

15 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Shadow pictures of luggage and inside the human body. High doses can kill cells. Lower doses can cause cells to become cancerous. X-rays EM radiation: Uses: Dangers: Hospital workers limit exposure to gamma and X-rays by standing behind lead shields or by leaving the room when the radiations are being used. X-ray radiation

16 © Boardworks Ltd of 20 © Boardworks Ltd of 30 X-rays can penetrate soft tissue but not b_____. X-rays are a_________ more by some materials than others. P____________ f____ is used to detect X-rays. How are X-ray slides formed? one bsorbed hotographic ilm

17 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Sun beds, fluorescent lamps and security marking. High doses can kill cells. Lower doses can cause cells to become cancerous. Ultraviolet EM radiation: Uses: Dangers: The higher the frequency of the radiation, the more dangerous it is. Therefore, gamma is more dangerous than X-rays or ultraviolet. Ultraviolet radiation

18 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Effects of EM radiation on living cells Infra red radiation is used in toasters, grills and radiant heaters. What effect do you think it has on your skin? Ultraviolet radiation can pass through skin to deeper tissues. What effect do you think the colour of the skin has on the amount of radiation that passes through it? The darker the skin, the more ultraviolet radiation is absorbed, and the less can reach into deeper soft tissues.

19 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Seeing, endoscopes. Blindness. Light EM radiation: Uses: Dangers: Light

20 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Remote controls (TV/VCR), radiant heaters, grills, optical fibre communication, night vision. Skin burns Infrared EM radiation: Uses: Dangers: Infrared radiation

21 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Night vision All objects above absolute zero emit infrared radiation. The hotter an object is, the more heat radiation it emits. Some animals and cameras can detect infrared radiation and are able to build up a heat picture. Which are the hottest/coolest parts of the image shown? light is hot dark is cold

22 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Satellite communication, mobile phone networks, cooking, radar. Internal tissue heating Microwaves EM radiation: Uses: Dangers: Microwave radiation

23 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Microwaves can be used in c because many foods contain w molecules. Microwaves of the right w are able to make the water molecules r. This causes the food to get h. How do microwaves cook food? ooking ater avelength esonate otter

24 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Communication and astronomy. Radio waves EM radiation: Uses: How do radio signals from the UK reach around the globe? The longer wavelength radio waves from a transmitter reflect off the Earth’s outer atmosphere (ionosphere). Radio waves

25 © Boardworks Ltd of 20 © Boardworks Ltd of 30 How can houses in the shadows of hills receive a radio signal? All electromagnetic radiation travels in straight lines. Remember diffraction? Radio waves diffract around the hill to the house. Radio waves

26 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Dispersion and Electromagnetic Radiation Contents Explaining dispersion The Electromagnetic Spectrum Summary activities Uses and dangers of EM radiation

27 © Boardworks Ltd of 20 © Boardworks Ltd of 30 dispersion – The splitting of light ray light into the range of colours that make up that light, e.g. when white light is split into the colours of the rainbow. electromagnetic spectrum – The complete range of electromagnetic waves that have different wavelengths (and frequencies). gamma rays – Electromagnetic waves with very short wavelengths, and which are given off by radioactive materials. infrared – Electromagnetic waves given off by hot objects, like grills and radiators, and used by TV remote controls. light – Electromagnetic waves that are detected by the eye. Glossary (1)

28 © Boardworks Ltd of 20 © Boardworks Ltd of 30 microwaves – Electromagnetic waves used for satellite communication, radar, mobile phone networks and cooking. prism – A triangular block of glass or plastic. radio waves – Electromagnetic waves with very long wavelengths, which are used to transmit radio and TV signals. spectrum – The range of all the colours of the rainbow that make up white light: red, orange, yellow, green, blue, indigo, violet. ultraviolet – Electromagnetic waves that are present in sunlight and cause some types of skin to darken. They also cause chemicals to glow in fluorescent lamps. X-rays – Electromagnetic waves with short wavelengths that are used for producing images of the inside of the body. Glossary (2)

29 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Anagrams

30 © Boardworks Ltd of 20 © Boardworks Ltd of 30 Multiple-choice quiz


Download ppt "© Boardworks Ltd 2004 1 of 20 © Boardworks Ltd 2005 1 of 30 KS4 Physics Dispersion and Electromagnetic Radiation."

Similar presentations


Ads by Google