The Electromagnetic Spectrum


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  • Light is just a small part of electromagnetic wave, what are others?
  • Electromagnetic spectrum song
  • When you are tuning the radio, you are actually searching for the right wavelength/frequency so that you can receive the signal sent out by the radio transmitting tower.
  • The antennae on your television set receive the signal, in the form of electromagnetic waves, that is broadcasted from the television station. It is displayed on your television screen.Cable companies have antennae or dishes which receive waves broadcasted from your local TV stations. The signal is then sent through a cable to your house. Why are car antennae about the same size as TV antennae?
  •  microwave oven cooks food because the  water  molecules inside it absorb the microwave radiation and thereby heat up and heat the surrounding food. 
  • The Electromagnetic Spectrum

    1. 1. Chapter 17: Part 2: Electromagnetic Spectrum
    2. 2. Can light travel through vacuum?
    3. 3. Light 1. Light belongs to a special group of waves called Electromagnetic Waves 2. Electromagnetic waves can travel through vacuum. 3. Light is not the only member of Electromagnetic spectrum. There are different types of waves in the spectrum.
    4. 4. What is Electromagnetic Spectrum? <ul><li>What is Light spectrum? </li></ul>What is Electromagnetic spectrum? It is a range of colours of light. It is a range of radiation.
    5. 5. The Electromagnetic Spectrum Gamma rays X-rays ultraviolet Infrared Visible light Microwaves Radio waves
    6. 6. The properties of Electromagnetic Waves <ul><li>They are transverse waves . </li></ul><ul><li>They do not require medium to travel from one point to another. Thus, they can travel through vacuum. </li></ul><ul><li>3. All of them travel at the speed of light of </li></ul><ul><li>3.0 x 10⁸ ms -1 in vacuum. </li></ul>
    7. 7. Karaoke! <ul><li>What you need to do? </li></ul><ul><li>Watch </li></ul><ul><li>Listen </li></ul><ul><li>Fill in the blanks on the lyrics </li></ul><ul><li>Sing-along! </li></ul>
    8. 8. From the TV station to your living room That is the work of radio waves Heating food in just seconds Microwaves do that Heat treatment for illness Take pictures in the dark They are even in your remote control Infrared radiation Red orange yellow green blue indigo violet That is the only part of the spectrum That can be seen by us The suntan on your skin Kill bacteria and viruses Used to detect forgery That is ultraviolet See your broken bones and my hidden bombs That is the work of x rays Kill cancer cells and sterilize Dangerous gamma rays do that Q: Which one has the highest level of energy?
    9. 9. Applications of EM waves
    10. 10. Radio waves <ul><li>Radio waves are used for radio communication. </li></ul><ul><li>A  radio tuner is necessary to tune in to a particular frequency to receive certain signals. </li></ul>
    11. 11. Radio waves <ul><li>It is also used for broadcasting i.e. television transmission. </li></ul><ul><li>The antennae on your television set receive the signal, in the form of electromagnetic waves , that is broadcasted from the television station. </li></ul>
    12. 12. Radio waves <ul><li>Radiowaves are also used in telecommunication such as cellular phone. </li></ul>
    13. 13. Microwaves <ul><li>Microwaves are used in oven to heat up food. </li></ul><ul><li>Water molecules in food absorb the microwave radiation, thereby heat up. </li></ul>
    14. 14. Microwaves <ul><li>Microwaves are also used in telecommunication such as satellite </li></ul><ul><li>For example, it is used in satellite TV and weather forecast. </li></ul>
    15. 15. Infrared <ul><li>Infrared radiation is used in remote controller, commonly for devices such as TVs, DVDs, Home theater systems etc. </li></ul>
    16. 16. Guess what is this?
    17. 17. Guess what is this?
    18. 18. Guess what is this?
    19. 19. Guess what is this?
    20. 20. Infrared <ul><li>It is also used in thermal imaging </li></ul><ul><li>The amount of radiation emitted by an object increases with temperature ; therefore, this technique allows one to see variations in temperature.  </li></ul>
    21. 21. Visible light enables us to see!
    22. 22. Visible light <ul><li>Visible light is also used in other imaging technologies such as microscopes, laser and fiber optics. </li></ul>
    23. 23. Ultraviolet <ul><li>Ultraviolet could be used to detect forgery. </li></ul>
    24. 24. Ultraviolet <ul><li>It is also used in the hospital to sterilise surgical tools i.e. to kill bacteria/viruses. </li></ul>
    25. 25. Dangers of UV light <ul><li>Besides being damaging to eyes, over-exposure might also cause skin cancer. </li></ul><ul><li>Therefore, it is important to protect ourselves from over-exposure of UV radiation. </li></ul>
    26. 26. X ray <ul><li>Medical imaging  is the technique and process used to create images of the human body for clinical purposes  </li></ul><ul><li>X-ray is often used for this purpose. </li></ul>
    27. 27. Gamma radiation <ul><li>Gamma radiation, is electromagnetic radiation of high frequency. </li></ul><ul><li>Therefore, it is highly damaging to our cells. </li></ul><ul><li>Despite their cancer-causing properties, gamma rays are also used to treat some types of cancer . </li></ul>