May 9, 2014

What Is The Electromagnetic Spectrum?

Hi, I’m Emerald Robinson. In this “What Is” video we’re going to take a closer look at the electromagnetic spectrum.

What we see as light is only a small part of the electromagnetic spectrum. The electromagnetic spectrum refers to the many types of radiation released from stars, including our own sun.

Electromagnetic radiation travels in waves. Frequency describes how many waves per second a wavelength produces. Wavelength measures the length of an individual wave in meters.

Scientists describe the electromagnetic spectrum as a long line. At one end lie radio waves, with the longest wavelengths and lowest frequencies in the spectrum.  A single radio wave has the length of a football field.

After radio waves come microwaves, which produce more energy due to shorter wavelengths and higher frequencies. Cell phones, radar, and microwave ovens use microwaves.

Next comes infrared light. The sun, fire, living creatures, and other heat sources all produce infrared light. While we cannot see infrared light, we feel it as heat.

Visible light occupies a narrow slice of the electromagnetic spectrum, nestled between infrared and ultraviolet light. Red wavelengths have the lowest frequencies and longest wavelengths of visible light. As you move from red through orange, yellow, green, blue and finally violet, wavelengths shorten and frequencies increase.

From visible violet light, we move into ultraviolet frequencies. Human skin produces vitamin D when exposed to ultraviolet light. But excessive ultraviolet light causes sunburns

Next, X-rays, which pass through soft tissue but not denser materials such as bone, are valuable for medical tests. X-rays also have security applications, such as airport baggage checks.

Gamma rays produce even shorter wavelengths, higher frequencies, and more energy. In comparison to the football field sized wavelengths of radio waves, gamma ray wavelengths are as small as atom nuclei.

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