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(Science Trek music)

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JOAN CARTAN-HANSEN, HOST:

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Over-the-air television and

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cellular streaming videos are

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possible because of something

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you can't see.

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The data for both are carried by

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electromagnetic radiation.

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That is energy that travels as

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waves.

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The electromagnetic spectrum is

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how we classify the different

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types of waves.

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At one end are radio waves, then

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microwaves, infrared waves,

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visible light, ultraviolet

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waves, X-rays, and at the end

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are gamma rays.

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Cell phones and television

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signals operate next to each

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other within the radio waves

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part of the spectrum.

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There is a limited amount of

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space on the electromagnetic

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spectrum, so who gets to use

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what part is regulated by the

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government.

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And that's important because

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signals can't overlap or

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interfere with each other, or

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they won't work.

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If you have a television set and

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an antenna, you can get

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over-the-air television channels

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for free.

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The picture quality is better,

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and you can get local

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information.

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And that's important in an

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emergency, or even if it's just

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an alert about closing schools

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and a snow day!

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For more information about

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television and streaming, check

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out the Science Trek website.

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You'll find it at

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ScienceTrek.org.