(Science Trek music) JOAN CARTAN-HANSEN, HOST: Over-the-air television and cellular streaming videos are possible because of something you can't see.
The data for both are carried by electromagnetic radiation.
That is energy that travels as waves.
The electromagnetic spectrum is how we classify the different types of waves.
At one end are radio waves, then microwaves, infrared waves, visible light, ultraviolet waves, X-rays, and at the end are gamma rays.
Cell phones and television signals operate next to each other within the radio waves part of the spectrum.
There is a limited amount of space on the electromagnetic spectrum, so who gets to use what part is regulated by the government.
And that's important because signals can't overlap or interfere with each other, or they won't work.
If you have a television set and an antenna, you can get over-the-air television channels for free.
The picture quality is better, and you can get local information.
And that's important in an emergency, or even if it's just an alert about closing schools and a snow day!
For more information about television and streaming, check out the Science Trek website.
You'll find it at ScienceTrek.org.