Exploring electromagnetic radiation

This exercise is a part of Educator Guide: Coating Provides Infrared Camouflage / View Guide

Directions for teachers:

Use this exercise to introduce or review the electromagnetic spectrum with your class. Begin by showing the NASA video “Introduction to the Electromagnetic Spectrum.” Students should work with a partner through prompts in “Properties of electromagnetic radiation.” Example answers are given. Then, students should choose a specific type of electromagnetic radiation to explore and research a technology that uses their chosen type. They can use the prompts in “Applications of technology using electromagnetic radiation” to prepare and give a brief presentation to their classmates.

Directions for students:

Properties of electromagnetic radiation:

Watch NASA’s “Introduction to the Electromagnetic Spectrum,” and answer the following prompts with a partner. Make sure you discuss the relationships between properties of electromagnetic radiation with your partner. Use additional resources if necessary. For instance, you could look up a diagram of the spectrum, such as this one provided by NASA

1. Define the following terms:

Electromagnetic radiation (make sure to include the name of each type):

Waves with electrical and magnetic properties that carry energy from one place to another. Classified by wavelength, the types of electromagnetic radiation are gamma rays, x-rays, ultraviolet, visible light, infrared, microwaves and radio waves.

Wavelength (and an appropriate unit used to measure it):

The distance between two consecutive crests or toughs of a wave, typically measured in meters (m). 

Frequency (and an appropriate unit used to measure it):

The number of crests that pass through a certain point in one second, typically measured in Hertz (Hz) or waves per second.

The speed of light (and an appropriate unit used to measure it):

The speed at which electromagnetic waves travel in a vacuum. The speed of light is typically measured in meters per second, and is equal to 3.0 x 108 m/s for all types of electromagnetic radiation.

2. Are the wavelength and frequency of electromagnetic waves directly or inversely related? Explain.

Wavelength and frequency are inversely related. As the wavelength gets longer, the frequency gets smaller — fewer waves will pass through a certain point in a second — and vice versa.

3. Are the frequency and energy of electromagnetic waves directly or inversely related?

Energy and frequency are directly related. As the energy increases, so does frequency — more waves will pass through a certain point in a second. As the energy decreases, fewer waves will pass through a certain point in a second.

4. Based on your answers to questions No. 2 and No. 3, what is the relationship between electromagnetic waves’ wavelength and energy?

Since energy and frequency are directly related, and frequency and wavelength are inversely related, wavelength and energy must be inversely related. As a wave’s energy grows, its wavelength gets shorter, and vice versa.

5. To better understand how different types of electromagnetic radiation relate to each other, rank gamma rays, infrared, ultraviolet and radio waves in order of increasing:


Gamma rays, ultraviolet waves, infrared waves, radio waves


Radio waves, infrared waves, ultraviolet waves, gamma rays


Radio waves, infrared waves, ultraviolet waves, gamma rays

6. What property is the same across all types of electromagnetic radiation in a vacuum?

All types of electromagnetic radiation travel at the same speed in a vacuum, the speed of light.

Applications of technology using electromagnetic radiation

With your partner, choose a type of electromagnetic radiation and research a technology that uses that specific type of radiation. Then, answer the questions below using NASA’s “Tour of the Electromagnetic Spectrum” and outside resources if necessary. The Science News archive is one of many useful resources. Use your answers to give a brief presentation on the technology to your classmates.

1. Does the video mention a technology you already knew about that uses electromagnetic radiation? Is there an application of that technology that was new to you, or surprised you? Explain.

2. Choose a type of electromagnetic radiation that you and your partner wish to explore and find a technology that uses this type of radiation. What is the technology called? What type of electromagnetic radiation does it use?

3. What is the goal or purpose of the technology?

4. Explain how the technology uses electromagnetic radiation.

5. Can this technology use only one type of electromagnetic radiation? Explain why or why not. 6. What are some other technologies that use your chosen type of electromagnetic radiation?