NASA Science

Introduction to The Electromagnetic Spectrum

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APA

National Aeronautics and Space Administration, Science Mission Directorate. (2009). Introduction to The Electromagnetic Spectrum. Retrieved , from Mission:Science website:

MLA

Science Mission Directorate. "Introduction to The Electromagnetic Spectrum" Mission:Science. 2009. National Aeronautics and Space Administration.

What is the EM Spectrum?

The electromagnetic spectrum is more familiar to you than you might think. The microwave you use to heat your food and the cell phones you use are part of the Electromagnetic Spectrum. The light that our eyes can see is also part of the electromagnetic spectrum. This visible part of the electromagnetic spectrum consists of the colors that we see in a rainbow - from reds and oranges, through blues and purples.

Left image is a prism bends the different wavelengths of light forming a rainbow. Right image is a diagram describing the differences in wavelengths Each color of the spectrum has a different wavelength. Red is the longest and violet is the shortest.

As white light travels through a prism, the waves of light are refracted. Each color of light has a slightly different wavelength and the longer wavelengths (red) bend at a lesser angle than the shorter wavelengths (blue). The result is the separation of the wavelengths by color forming a rainbow. Conversely, a second prism could combine all the wavelengths back into white light.

An illustration of the electromagnetic spectrum.

Waves in the electromagnetic spectrum vary in size from very long radio waves the size of buildings, to very short gamma-rays smaller than the size of the nucleus of an atom.

Electromagnetic waves (or EM waves) are similar to ocean waves in that both are energy waves — they transmit energy. EM waves are produced by the vibration of charged particles and have electrical and magnetic properties. But unlike ocean waves that require water, EM waves travel through the vacuum of space at the constant speed of light.

Ocean waves at the beach.
Waves rippling through a flag

Have you ever ridden a wave in the ocean? Ocean waves travel on the surface of the water. You can see them and you can feel them. As you swim through the water, you can even make your own waves. Have you ever seen a flag on a windy day? The wind creates waves in the flag. Both the waves in the flag and the ocean waves are waves that you can see. There are other kinds of waves. We cannot see these waves, but we experience them every day. These waves are called electromagnetic waves.

Sound is also a type of wave that we cannot see. Like ocean waves, sound waves something to travel through like waves through the ocean or through a flag. Sound can travel through air because air is made of molecules. These molecules carry the sound waves by bumping into each other, like dominoes knocking each other over. Sound can travel through anything made of molecules - even water! There is no sound in space because there are no molecules there to transmit the sound waves. Electromagnetic waves are different from sound waves because they do not need molecules to travel. This means that electromagnetic waves can travel through air and solid materials - but they can also travel through empty space. This is why astronauts on spacewalks use radios to communicate. Radio waves are one kind of electromagnetic wave.

A balloon rubbed on a child's head causing her hair to be attracted to the balloon.
A photo of a magnet

Electricity can be static, like what holds a balloon to the wall or makes your hair stand on end.Magnetism can also be static like a refrigerator magnet. But when they change or move together, they make waves - electromagnetic waves.

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Citations

APA

National Aeronautics and Space Administration, Science Mission Directorate. (2009). Introduction to The Electromagnetic Spectrum. Retrieved , from Mission:Science website:

MLA

Science Mission Directorate. "Introduction to The Electromagnetic Spectrum" Mission:Science. 2009. National Aeronautics and Space Administration.