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Electromagnetic spectrum

Electromagnetic spectrum. Learning today – copy. The main features and characteristics of the Electromagnetic spectrum The uses and dangers of EM spectrum. Electromagnetic spectrum Mini-book – Due 17 th September. One type of EM wave for each page Each page should contain the wavelength

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Electromagnetic spectrum

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  1. Electromagnetic spectrum

  2. Learning today – copy • The main features and characteristics of the Electromagnetic spectrum • The uses and dangers of EM spectrum

  3. Electromagnetic spectrum Mini-book – Due 17th September • One type of EM wave for each page • Each page should contain the wavelength • Each page should contain uses and other interesting information (including dangers) • Attractive to look at (and funny?)-

  4. The EM spectrum is a continuous spectrum

  5. Visible light

  6. Visible light λ ≈ 700 nm λ ≈ 420 nm

  7. Ultraviolet waves λ ≈ 700 - 420 nm

  8. Ultraviolet waves λ ≈ 700 - 420 nm λ ≈ 10 – 100 nm

  9. X-rays λ ≈ 700 - 420 nm λ ≈ 10 – 100 nm

  10. X-rays λ ≈ 700 - 420 nm λ ≈ 10 – 100 nm λ ≈ 1 – 0.01 nm

  11. Gamma rays λ ≈ 700 - 420 nm λ ≈ 10 – 100 nm λ ≈ 1 – 0.01 nm

  12. Gamma rays λ ≈ 700 - 420 nm λ ≈ 10 – 100 nm λ ≈ 0.001 – 0.00001 nm λ ≈ 1 – 0.01 nm

  13. Infrared waves λ ≈ 700 - 420 nm λ ≈ 10 – 100 nm λ ≈ 1 – 0.01 nm λ ≈ 0.001 – 0.00001 nm

  14. Infrared waves λ ≈ 700 - 420 nm λ ≈ 10 – 100 nm λ ≈ 10-4 - 10-6 m λ ≈ 1 – 0.01 nm λ ≈ 0.001-0.00001nm

  15. Microwaves λ ≈ 700 - 420 nm λ ≈ 10-4 - 10-6 m λ ≈ 10 – 100 nm λ ≈ 1 – 0.01 nm λ ≈ 0.001-0.00001nm

  16. Microwaves λ ≈ 700 - 420 nm λ ≈ 10-4 - 10-6 m λ ≈ 10 – 100 nm λ ≈ 1 – 0.01 nm λ ≈ 10-2 - 10-3 m λ ≈ 0.001-0.00001nm

  17. Radio waves λ ≈ 700 - 420 nm λ ≈ 10-4 - 10-6 m λ ≈ 10 – 100 nm λ ≈ 1 – 0.01 nm λ ≈ 10-2 - 10-3 m λ ≈ 0.001-0.00001nm

  18. Radio waves λ ≈ 700 - 420 nm λ ≈ 10-4 - 10-6 m λ ≈ 10 – 100 nm λ ≈ 1 – 0.01 nm λ ≈ 10-2 - 10-3 m λ ≈ 10-1 - 103 m λ ≈ 0.001-0.00001nm

  19. Electromagnetic spectrum λ ≈ 700 - 420 nm λ ≈ 10-4 - 10-6 m λ ≈ 10 – 100 nm λ ≈ 1 – 0.01 nm λ ≈ 10-2 - 10-3 m λ ≈ 10-1 - 103 m λ ≈ 0.001-0.00001nm

  20. Electromagnetic spectrum Long Wavelength Short Wavelength

  21. Electromagnetic spectrum Long Wavelength Short Wavelength High Frequency Low Frequency

  22. What do they all have in common? λ ≈ 700 - 420 nm λ ≈ 10-4 - 10-6 m λ ≈ 10 – 100 nm λ ≈ 1 – 0.01 nm λ ≈ 10-2 - 10-3 m λ ≈ 10-1 - 103 m λ ≈ 10-12 - 10-14 m

  23. What do they all have in common? copy please • They can travel in a vacuum • They travel at 3 x 108m.s-1 in a vacuum (the speed of light) • They are transverse • They are electromagnetic waves (electric and magnetic fields at right angles to each oscillating perpendicularly to the direction of energy transfer)

  24. What else do you need to know?

  25. Electromagnetic spectrum Long Wavelength Short Wavelength High Frequency Low Frequency

  26. Uses of microwaves • Satellite TV and cellular phones

  27. Uses of Infrared waves • Remote controls for TVs and intruder alarms

  28. Uses of X-rays • Medicine and security

  29. Dangers of microwaves and X-rays

  30. You need top know the speed of light (c) • 300 000 000 m/s • 3 x 108 m/s

  31. Mini-book

  32. Mini-book • Finish for homework. • Due Thursday • 21st June 2012

  33. Electromagnetic spectrum Mini-book • One type of EM wave for each page • Each page should contain the wavelength • Each page should contain uses and other interesting information (including dangers) • Attractive to look at (and funny?) • Due Thursday 21st June.

  34. Analogue and digital signals –copy Communication signals may be analogue or digital. Analogue signals vary continuously in amplitude between zero and some maximum level. Digital signals only have two voltage levels, for example +5V and 0V.

  35. Learning today – copy • Analogue and digital signals • The uses and dangers of EM spectrum

  36. ANALOGUE DIGITAL Examples of analogue and digital systems

  37. Regenerator ‘Noisy’ pulse in ‘Clean’ pulse out Advantages of using digital signals- copy • Less interference than with analogue signals. Interference causes a hissing noise with analogue radio. This does not happen with digital signals because regenerator circuits are used to clean ‘noisy’ pulses. So a digital signal has a higher quality than an analogue one.

  38. 2. Much more information can be sent. Copy Digital pulses can be made very short so more pulses can be carried each second. Different signals can be sent together by a process called multiplexing. 3. Digital signals are easily processed by computers.Copy Computers are digital devices!

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