The Electromagnetic Spectrum

Lesson Plan - Get It!

Audio:

In previous Related Lessons, found in the right-hand sidebar, you learned that wavelength is the distance between two crests or two troughs.

You also learned that frequency is the number of wavelengths on a given light wave over a given period of time, usually a second.

• Were you able to identify the relationship between wavelength and frequency by looking at the two transverse light waves above?

Share your idea with your parent or teacher.

You should have noticed that the greater the frequency, the shorter the wavelength. In this lesson, you will learn about the electromagnetic spectrum. Understanding the relationship between wavelength and frequency will help you better understand this concept.

Remember, light waves are waves of energy, and each wave carries a different amount of energy. The amount of energy a wave has is proportional to its frequency. The greater the frequency, the more energy a light wave has. The electromagnetic spectrum arranges types of light waves according to the amount of energy they have, as in this chart below:

_{Image by NASA, via Wikimedia Commons, is in the public domain in the United States because it was solely created by NASA. NASA copyright policy states that "NASA material is not protected by copyright unless noted".}

According to scientists, there are seven types of light waves, and they are all arranged on the electromagnetic spectrum according to the amount of energy they possess. The different parts of the electromagnetic spectrum include radio waves, microwaves, infrared waves, visible waves, ultraviolet waves, x-rays, and gamma rays. Use the picture to help you answer the following questions. Explain your answers to your teacher or parent:

• Which part of the electromagnetic spectrum has the most energy? The least energy?
• What type of light wave has the longest wavelength? The shortest wavelength?
• What type of light wave has the greatest frequency? The smallest frequency?

The part of the electromagnetic spectrum that has the most energy is gamma rays. You know gamma rays have the most energy because they have the greatest frequency and the shortest wavelength. The wavelength of a gamma ray is as small as the nucleus of an atom.

The part of the electromagnetic spectrum that has the least energy is radio waves. You know radio waves have the least energy because they have the smallest frequency and longest wavelengths. Radio waves can be as long as skyscrapers are tall.

You are going to learn which objects emit each type of wave while watching an interactive and reading an article. As you watch the interactive and read the article, take notes. Be sure to write:

• Examples of objects that can produce each type of light wave.
• What types of waves humans can see.
• What types of waves the sun produces.

Now, watch and take notes on the BBC's The electromagnetic spectrum activity. You can pause and rewind the interactive at any point to make sure you are getting all the information.

Then, continue taking notes as you read Introduction to the Electromagnetic Spectrum by Science Mission Directorate, Mission: Science, 2010, NASA. Be sure to click the links at the bottom of the page to read about each part of the electromagnetic spectrum.

• Did you find examples of objects that produce each type of wave?

Share your examples with your teacher or parent.

The only types of waves that humans can see are visible waves. Visible waves are what enable humans to see in color. You will learn more about visible waves in the Related Lessons in the "All About Light" series, found in the right-hand sidebar.

The sun produces a unique light. Sunlight consists of the entire electromagnetic spectrum. It produces every type of light wave!

Make sure you have carefully studied each of the sites provided. Then, when you are ready, move onto the Got It? section to assess what you have learned about the electromagnetic spectrum.