What is electromagnetic radiation?
Electromagnetic energy is a term used to describe all the different kinds of energies released into space by stars such as the Sun. These kinds of energies include some that you will recognize and some that will sound strange. They include: * Radio Waves
* TV waves
* Radar waves
* Heat (infrared radiation)
* Ultraviolet Light (This is what causes Sunburns)
* X-rays (Just like the kind you get at the doctor's office) * Short waves
* Microwaves, like in a microwave oven
* Gamma Rays
All these waves do different things (for example, light waves make things visible to the human eye, while heat waves make molecules move and warm up, and x rays can pass through a person and land on film, allowing us to take a picture inside someone's body) but they have some things in common. They all travel in waves, like the waves at a beach or like sound waves, and also are made of tiny particles. Scientists are unsure of exactly how the waves and the particles relate to each other. The fact that electromagnetic radiation travels in waves lets us measure the different kind by wavelength or how long the waves are. That is one way we can tell the kinds of radiation apart from each other. Although all kinds of electromagnetic radiation are released from the Sun, our atmosphere stops some kinds from getting to us. For example, the ozone layer stops a lot of harmful ultraviolet radiation from getting to us, and that's why people are so concerned about the hole in it. We humans have learned uses for a lot of different kinds of electromagnetic radiation and have learned how to make it using other kinds of energy when we need to. DS1 would not be able to communicate with Earth, for example, if it could not produce radio waves.
Friend and Foe
Taming the Wild Energies
We have the power! Whenever we turn on a computer, a cell phone, a stove, a radio; light a match; get an x-ray for a broken leg, have a CAT-scan; run a nuclear power plant, explode a hydrogen bomb, focus a laser beam, or put on sunscreen, we are trying to tame electromagnetic radiation.
When it is your friend, it is being used by your TV to present glowing images on a screen, or being used to pop popcorn in that bag in the microwave. Right now, friendly electromagnetic radiation is in the lightbulb above you. When it is your foe, it is in the form of X-Rays, Gamma Rays, or even "Galactic Cosmic Rays" which can penetrate the cells of your body and create cancers. As your foe, electromagnetic radiation comes in the form of Uranium in the soil in the Rocky Mountains, or Radon in your basement.
Electromagnetic energy is all around us. It moves at the speed of light. It cooks our food, enters our eyes, bathes our skin and heats us, penetrates our bodies, threatens our cells, provides plants with the energy to conduct photosynthesis. Some forms of it are relatively easy to keep under control. Some forms of it are hard to control and can be very dangerous to human beings. Let's dare to ask some questions to learn more: • What is electromagnetic radiation?
• Where does it come from?
• How is it created?
• Is radiation all the same or different?
• Why is an understanding of electromagnetic radiation important for the space station?
| What is Electromagnetic Radiation?
First, electromagnetic radiation is referred to by a number of different names: electromagnetic energy, electromagnetic waves, radiation, even heat. The various names certainly create confusion! Electromagnetic energy becomes more confusing when we refer to it as both friend and foe. In fact, electromagnetic energy can behave in two completely different disguises at the same time.
Disguise number one: Waves
Read the following sentences carefully and pay close attention to the highlited words: Electromagnetic waves are emitted from any source of energy, whether a simple heated metal pan, an...
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