Electro Magnetic Spectrum

Electro Magnetic Spectrum

1. Electromagnetic Radiation

   • Electromagnetic Radiation is simply waves of energy travelling through space - or through matter.
   • Radio, microwaves, UV, visible light and gramma rays have completely different effects, but they're all exactly the same kind of thing: electromagnetic radiation (EMR).

2. Electromagnetic waves

   • Electromagnetic waves transmit energy from one place to another.
   • Travel through air at the speed of light 300 000 000 metres per second.
   • Moves as a transverse wave.

3. Types of waves:

   • Microwaves
     • Are used in radar and communication systems.
     • Shorter microwaves are used for cooking.
     • The microwaves are absorbed by the food molecules, causing them to vibrate and heat up. But because he heating occurs inside the food without warming the air, the food can cook unevenly.
   • Visible light
     • Consists of different colours. Although it represents only a small part of the electromagnetic spectrum, it is the only band visible to our eyes.
     • It is essential for much for the life on earth. The process of photosythnesis in green plants cannot take place without visible light.
   • Infrared waves
     • Are just below visible red light in the electromagnetic spectrum.
     • They are emitted by all objects and sensed as heat.
   • Radio waves
     • Low energy waves that are used to communicate over long distances through radio and television.
     • They are produced through vibrating electrons in a transmitting aerial.
     • They are used for communication because they bend around the earth's surface when transmitted.
   • UV light
     • Is radiation with a higher requency than violet light. It is invisible to the human eye.
     • Sunlight contains UV light in addition to infrared and visible light.
     • It is needed by humans o help the body produce vitamin D.
   • X rays
     • Are very high frequency waves, and carry a lot of energy. They will pass through most substances.
     • It has such high energy that it can damage cells and tissues, and the genetic materials inside cells.
   • Gamma Rays
     • Have a wavelength of about one- hundred- billionth of a metre.
     • They even have more energy than X-rays and can cause serious damage o living cells.
     • They can be used to kill cancer cells, used in medical diagnosis and can find weaknesses in metals.

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