More on EM waves

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  • Created by: alexda
  • Created on: 17-05-14 19:02
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  • More on electromagnetic waves
    • 3. Infrared
      • Infrared radiation can be used in cooking e.g. in grills and toasters.
      • Remote controls transfer information to televisions and DVD players using infrared.
      • Infrared can be used for short range communications: transmitting information between mobile phones or computers.
      • Infrared sensors are used in security systems e.g. burglar alarms. These sensors detect heat from the body.
      • Optical fibres use infrared to transmit data
      • Infrared radiation is also known as heat radiation.
      • If the human body is exposed to too much infrared radiation, it can cause skin burns.
      • Herschel discovered infrared when experimenting with sunlight and a prism:
        • 1. Using a prism to break up visible light he put a thermometer in the different colours. He found that the temperature rose as he moved the thermometer from violet to red.
          • 2. He then measured the temperature where there was no visible light, at the red end of the spectrum. The temperature was the highest: he had discovered infra red,an invisible type of radiation.
    • 4. Visible Light
      • Photography
      • Vision
      • Illuminatiion
    • 5. Ultraviolet
      • Sunburn happens when surface skin cells have been damaged by absorbing UV rays in sunlight.
        • This can cause cell mutation or destruction and skin cancer. The sunlight can also cause eye damage.
      • He used silver chloride, which turns black when exposed to light to measure how quickly silver chloride coated strips changed when exposed to different colours of light. This happened fastest when exposed to the invisible rays at the violet end of the spectrum.
      • Security pens
      • Sunbeds
      • Fluorescent lamps


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