Daffodil International University
Science & Information Technology => Science Discussion Forum => Topic started by: bidita on March 23, 2011, 03:41:52 PM
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Do you listen to the radio, watch TV, or use a microwave oven? All these devices make use of electromagnetic waves. Radio waves, microwaves, visible light, and x rays are all examples of electromagnetic waves that differ from each other in wavelength..
(a) Longer wavelength; (b) shorter wavelength.
Electromagnetic waves are produced by the motion of electrically charged particles. These waves are also called "electromagnetic radiation" because they radiate from the electrically charged particles. They travel through empty space as well as through air and other substances.
Scientists have observed that electromagnetic radiation has a dual "personality." Besides acting like waves, it acts like a stream of particles (called "photons") that have no mass. The photons with the highest energy correspond to the shortest wavelengths.
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Electromagnetic radiation is a term used to describe a stream of energy-bearing particles that travels outward from an electromagnetic source. The energy in these streams can vary extensively in power, and is measured by the electromagnetic spectrum. Electromagnetic radiation can be beneficial, harmless or extremely dangerous to humans, depending on the source, level of radiation, and duration of exposure.
There are both natural and man-made sources of electromagnetic radiation. The sun, for instance, is an intense source of radiation that can have both positive and negative effects on living things. The sun also produces both visible and invisible electromagnetic streams. Ultraviolet rays from the sun are invisible and cause sunburn and skin cancer if overexposure occurs. A rainbow, however, is a visible and harmless part of the electromagnetic effect caused by the sun, as human eyes detect the visible wavelengths of light as different colors.
Source: http://www.wisegeek.com/what-is-electromagnetic-radiation.htm
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Human body can protect radiation up to a limit which is called permissible limit. For that we need to follow a guideline. Thanks…….
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Electromagnetic radiation is present in all electrical appliances, but the strongest radiation comes from
mobile phones
wireless phones
monitors
photocopiers
microwave ovens
hairdryers
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Radiation from X-ray, gamma ray has more Penetrating power and also have ionizing power. So we need avoid that type of radiation.