The EM Spectrum

1. The EM Spectrum Lesson 01: Dispersion Lesson 02/03: The EM Spectrum Lesson 04: Pupil Research Lesson 05: Pupil Presentations

2. 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

3. Dispersion20/08/2014 • Aim: • To be able to explain the cause of dispersion • To explain the nature of the electromagnetic spectrum Starter:

5. 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. Richard Of York Gave Battle In Vain How do you remember the order of the colours? Which colour is refracted the most? Red light is refracted least. Violet light is refracted the most.

6. Colour, Wavelength and Amplitude

7. Newton’s Disk

8. Dispersion Summary Red/violet Refracted more/less by glass Longer/shorter wavelength Red/violet Refracted more/less by glass Longer/shorter wavelength

13. 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.

14. 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.

15. Tests

17. Which is Longer?

19. A Spiral?

20. Definitions All Electromagnetic waves are energy waves They can travel through a vacuum They all travel at the speed of light (300 000 000 m/s) We group them by their properties and hence uses, inside each group is a range of frequencies. Copy

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

22. The EM Spectrum recap • Aim: • To explain the dangers and uses of the EM Spectrum Starter: 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 TRUE/FALSE TRUE/FALSE TRUE/FALSE TRUE/FALSE

23. The Electromagnetic Spectrum20/08/2014 • Aim: • To explain the uses and dangers of the EM Spectrum

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

25. Uses and dangers of EM radiation Copy the Top of the following table into your books (we will fill it in as we go)

26. GAMMA RAYS

27. High Level nuclear waste Microbes can be killed using gamma radiation

28. Increasing dose tumour healthy brain tissue view through the head Gamma rays can be used to treat brain tumours skull

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

30. X-rays

31. 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.

32. X-ray tube Detection of broken bones in the body

33. Customs • X-Rays are used to scan luggage in customs • Movie

34. Damage to organs. X-rays can penetrate to the vital organs inside the body.

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

36. ULTRA VIOLET

37. UV 39637 Visible light (longer wavelength)

38. Movie Friends

39. The effect of UV on cells Outer dead skin cells Outer dead skin cells Living skin cells Living skin cells

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

41. Movie Shorter Wavelengths

42. Visible Light

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

44. EM Radiation:Uses:Dangers: Light Photography and endoscopes Blindness

45. Infrared

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

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

48. How do infrared waves cook food?

49. 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 Walking in the Woodland Fireman dark is cold

50. Uses of infrared – activity