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Microwaves presentation Microwaves presentation Presentation Transcript

  • Microwaves
  • What are microwaves?
    Microwave radiation are the radiating wave movements in which microwave energy travels. The wavelengths can be from as long as one meter to as short as one millimeter. Microwaves have a frequency range of 0.3 Ghz to 300 Ghz.
    They are found between the radio waves and the infrared waves in the electromagnetic spectrum.
  • Where can we find them?
    Microwaves take a straight line path. They can pass through non-metal materials such as plastic and glass, but get reflected off metal surfaces.
    Microwaves are absorbed by materials that have a high water content and produce heat, some examples are food, fruits, vegetables etc. This is where the microwave kitchen appliances work, the microwave oven (in the picture) is used for heating up our food by microwaves.
  • Microwave ovens
    A microwave oven consists: a high voltage transformer, an electron tube called magnetron , a wave guide fan and a oven chamber. The transformer passes electric energy to the magnetron and the magnetron converts this electric energy into microwave radiation. The microwaves are reflected in the oven chamber and are absorbed by the food.
  • Absorption of microwaves by food.
    The microwave absorption, happens when the water molecules in the food begin to vibrate. This molecular movement produces heat and the resultant heat cooks the food. Foods that have higher concentrations of water molecules cook faster.
  • Concerns about microwaves.
    Concerns about microwaves turning food radioactive are baseless. The radiation in microwave refers to the way in which microwaves move, not radioactivity.
    Microwaves are of a non-ionizing character. They do not have the energy to cause chemical changes in substances as would happen in the case of radioactivity.
    The danger of microwaves is that body tissue can be affected in the same way that food is. Microwaves can cause burns, eye cataracts and other injuries. It however, would take high levels of microwaves for this to happen. The levels of microwave radiation in kitchen appliances are very low.
  • References:
    http://en.wikipedia.org/wiki/Microwave
    http://www.wisegeek.com/what-is-microwave-radiation.htm
    http://www.gallawa.com/microtech/mwave.html
    http://www.fda.gov/Radiation-EmittingProducts/ResourcesforYouRadiationEmittingProducts/Consumers/ucm142616.htm
    Thank you for watchingBy Maria Voureka