StopwatchStopwatch Graph HomeGraphHome The EM Spectrum Lesson 01: Dispersion Lesson 02/03: The EM Spectrum Lesson 04: Pupil Research Lesson 05: Pupil Presentations

StopwatchStopwatch Graph HomeGraphHome Teachers Notes The key words are copied as a list at the start of the topic and the definitions are filled in as the topic progresses. Text in Yellow or Green is for pupils to copy or are instructions. Text in Copperplate is a hyperlinks to a worksheet, experiment sheet, handout, movie, internet site or other places inside the PowerPoint. Copperplate For the links to work the external documents must keep the same name and be in the same folder as the PowerPoint

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Stopwatch Graph HomeGraphHome EM Double and Triple Science Syllabus The electromagnetic spectrum understand that light is part of a continuous electromagnetic spectrum which includes radio, microwave, infra-red, visible, ultraviolet, X-ray and gamma ray radiations and that all these waves travel at the same speed in free space recall the order of the electromagnetic spectrum in decreasing wavelength and increasing frequency, including the colours of the visible spectrum recall some of the uses of electromagnetic radiations, including radio waves: broadcasting and communications microwaves: cooking and satellite transmissions infra-red: heaters and night-vision equipment visible light: optical fibres and photography ultraviolet: fluorescent lamps X-rays: observing the internal structure of objects and materials and medical applications gamma rays: sterilising food and medical equipment recall the detrimental effects of excessive exposure of the human body to electromagnetic waves, including microwaves : internal heating of body tissue infra-red : skin burns ultraviolet : damage to surface cells and blindness gamma rays : cancer, mutation

StopwatchStopwatch Graph HomeGraphHome Dispersion 19/05/2015 Aim: To be able to explain the cause of dispersion To explain the nature of the electromagnetic spectrum Starter:

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StopwatchStopwatch Graph HomeGraphHome 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

StopwatchStopwatch Graph HomeGraphHome Colour, Wavelength and Amplitude

StopwatchStopwatch Graph HomeGraphHome Newton’s Disk

StopwatchStopwatch Graph HomeGraphHome Dispersion Summary Red/violet Refracted more/less by glass Longer/shorter wavelength Red/violet Refracted more/less by glass Longer/shorter wavelength

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StopwatchStopwatch Graph HomeGraphHome Addition of Colours There are three primary colours: Red Blue Green By adding together the primary colours you can make other colours. For example red and blue make green. This is different to the reflection of light this is an optical illusion due to the way your eyes work.

StopwatchStopwatch Graph HomeGraphHome Colour Blindness No functioning cones: See black and white, have problems with daylight, because it is too bright for them; they also lack visual acuity One type of cone working: see colours only as variations in intensity, similar to black-and-white or one colour images Red Cone Not Working: typically only two (yellow, blue) can be distinguished - yellow comprises red, orange, yellow, and green, blue coincides with blue and purple Green cone not working; green cannot be distinguished from certain combinations of red and blue; this is the most common type of colour deficiency Blue cone not working: longer wavelengths appear as red and the shorter ones as bluish- green; this colour deficiency is very rare More than 8% of the male and about 0.04% of the female population have some sort of colour anomaly or deficiency.

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StopwatchStopwatch Graph HomeGraphHome Which is Longer?

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StopwatchStopwatch Graph HomeGraphHome Definitions All Electromagnetic waves are energy waves They can travel through a vacuum They all travel at the speed of light ( m/s) We group them by their properties and hence uses, inside each group is a range of frequencies. Copy

StopwatchStopwatch Graph HomeGraphHome Electromagnetic Spectrum Radio Micro Infra- Red Light Ultra- Violet X rays Gamma Wavelength ( ) increases High frequency Short wavelength High energy Most penetrating High frequency Short wavelength High energy Most penetrating Low frequency Long wavelength Low energy Least penetrating Low frequency Long wavelength Low energy Least penetrating

StopwatchStopwatch Graph HomeGraphHome The EM Spectrumrecap Aim: To explain the dangers and uses of the EM 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 Starter:

StopwatchStopwatch Graph HomeGraphHome The Electromagnetic Spectrum 19/05/2015 Aim: To explain the uses and dangers of the EM Spectrum

StopwatchStopwatch Graph HomeGraphHome Electromagnetic Spectrum Radio Micro Infra- Red Light Ultra- Violet X rays Gamma Wavelength ( ) increases Remember My Instructions Visible Under X – Ray Glasses High frequency Short wavelength High energy Most penetrating Low frequency Long wavelength Low energy Least penetrating

StopwatchStopwatch Graph HomeGraphHome Uses and dangers of EM radiation Copy the Top of the following table into your books (we will fill it in as we go) RadiationUsesDangers Gamma X-rays Ultraviolet Light Infra red Microwaves Radio waves

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StopwatchStopwatch Graph HomeGraphHome High Level nuclear waste Microbes can be killed using gamma radiation

StopwatchStopwatch Graph HomeGraphHome Increasing dose tumour view through the head skull healthy brain tissue Gamma rays can be used to treat brain tumours

StopwatchStopwatch Graph HomeGraphHome EM Radiation: Uses: Dangers: sterilising surgical equipment and food, killing cancer cells. High doses can kill cells. Lower does can cause cancer (brain, liver, bone, leukemia…) Sterility Gamma

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StopwatchStopwatch Graph HomeGraphHome X-ray tube Jumbo jet wings are regularly checked in this way to see if any micro-cracks have developed. These small cracks are too small to see any other way and could have fatal consequences.

StopwatchStopwatch Graph HomeGraphHome X-ray tube Detection of broken bones in the body

StopwatchStopwatch Graph HomeGraphHome Customs X-Rays are used to scan luggage in customs Movie

StopwatchStopwatch Graph HomeGraphHome Damage to organs. X-rays can penetrate to the vital organs inside the body.

StopwatchStopwatch Graph HomeGraphHome EM Radiation: Uses: Dangers: Shadow pictures of luggage and inside the human body. High doses can kill cells. Lower doses can cause cancer Sterility X rays

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StopwatchStopwatch Graph HomeGraphHome UV Visible light (longer wavelength)

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StopwatchStopwatch Graph HomeGraphHome Outer dead skin cells Living skin cells The effect of UV on cells

StopwatchStopwatch Graph HomeGraphHome EM Radiation: Uses: Dangers: Sun beds, fluorescent lamps and security marking. Sun Burn. Skin cancer Blindness Ultraviolet

StopwatchStopwatch Graph HomeGraphHome Movie Shorter Wavelengths

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StopwatchStopwatch Graph HomeGraphHome Optical Fibres Optical fibres, that are used in communication, use total internal reflection. What are the applications of total internal reflection?

StopwatchStopwatch Graph HomeGraphHome EM Radiation: Uses: Dangers: Photography and endoscopes endoscopes Blindness Light

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StopwatchStopwatch Graph HomeGraphHome During the day the earth warms up as it absorbs short wave infrared rays from the sun During the night the earth loses longer wavelength infrared rays by radiating them into space and the earth cools down.

StopwatchStopwatch Graph HomeGraphHome Too much water vapour and carbon dioxide in the atmosphere will trap the infrared rays and cause the earth to overheat This effect is called the greenhouse effect (or global warming)

StopwatchStopwatch Graph HomeGraphHome How do infrared waves cook food?

StopwatchStopwatch Graph HomeGraphHome 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 Fireman Walking in the Woodland

StopwatchStopwatch Graph HomeGraphHome Uses of infrared – activity

StopwatchStopwatch Graph HomeGraphHome EM Radiation: Uses: Dangers: Remote controls, radiant heaters, grills, optical fibre communication, night vision, Mobile Phones Skin burns Infrared

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StopwatchStopwatch Graph HomeGraphHome Communications satellites use microwaves The microwaves can pass straight through the ionosphere Their shorter wavelength (higher frequency) means they are more penetrating than radio waves

StopwatchStopwatch Graph HomeGraphHome Microwave oven You will need to understand how microwaves cook food The microwaves have the exact wavelength (frequency) to be absorbed by the water molecules The molecules move faster The water temperature increases

StopwatchStopwatch Graph HomeGraphHome Demo DO NOT do this at Home Beaker with water in the microwave Light Bulb in the beaker Heat for 5 seconds (until the light bulb lights)

StopwatchStopwatch Graph HomeGraphHome EM Radiation: Uses: Dangers: Satellite communication, mobile phones, cooking, RADAR. Internal tissue heating. Microwaves

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StopwatchStopwatch Graph HomeGraphHome Short wave radio and TV waves are broadcasted to line of sight aerials. They cannot travel large distances because of the curvature of the earth. aerial 1 aerial 2

StopwatchStopwatch Graph HomeGraphHome Short wave radio and TV waves are broadcasted to line of sight aerials. They cannot travel large distances because of the curvature of the earth. transmitter

StopwatchStopwatch Graph HomeGraphHome Radio waves can reach the aerial if we use a charged layer in the atmosphere (the IONOSPHERE). IONOSPHERE The radio waves are reflected by this charged layer Remember that all types of light waves (electromagnetic radiation) can be reflected aerial

StopwatchStopwatch Graph HomeGraphHome EM Radiation: Uses: Dangers: Communication and astronomy. Radio waves

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StopwatchStopwatch Graph HomeGraphHome The electromagnetic spectrum

StopwatchStopwatch Graph HomeGraphHome Energy of electromagnetic waves

StopwatchStopwatch Graph HomeGraphHome Effect of electromagnetic waves

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StopwatchStopwatch Graph HomeGraphHome EM Questions 1)Match up the following parts of the electromagnetic spectrum with their uses : Gamma raysAllow us to see Radio wavesRemote Controls Ultra Violet‘See’ broken bones VisibleCarry TV signals MicrowavesRADAR X raysSterilise equipment Infra RedCauses sun-tans

StopwatchStopwatch Graph HomeGraphHome EM Questions 2) Which radiations are missing from below? Gamma AUltravioletLightInfrared BRadio waves A.___________ B.___________ X rays Microwaves

StopwatchStopwatch Graph HomeGraphHome Electromagnetic Spectrum

StopwatchStopwatch Graph HomeGraphHome Movie Uses of EM Spectrum

StopwatchStopwatch Graph HomeGraphHome The EM Spectrumrecap Aim: To explain the dangers and uses of the EM Spectrum

StopwatchStopwatch Graph HomeGraphHome Research 19/05/2015 Aim: Prepare a presentation on part of the EM Spectrum Task: Groups of 2 or 3 Your presentation should last 3-4 minutes Everyone must talk You must explain at least the uses and dangers

StopwatchStopwatch Graph HomeGraphHome Pupil Presentations 19/05/2015 Aim: Make a presentation on your part of the EM Spectrum