Waves That Work For Us

By the end of this lesson, you will be able to explain how different electromagnetic waves are used in technology, medicine, and science.

Think about a Friday night football game in Texas. The stadium lights flood the field with visible light, your phone gets a text through invisible radio waves, and the trainer sends an injured player for an X-ray at the clinic. All of those are electromagnetic waves, which are waves of electric and magnetic energy that can travel through empty space without needing air or water to carry them. They all move at the speed of light, but they differ in wavelength, which is the distance from one wave crest to the next.

Waves with long wavelengths carry less energy. Radio waves and microwaves are the longest, and we use them for wireless technologies like cell phones, Wi-Fi, and car radios, and for heating leftovers in a microwave oven, where the waves make water molecules in the food vibrate faster. Infrared waves carry heat and show up in TV remotes and night-vision cameras.

Visible light is the only part we can see, and it does more than light a room. In fiber optics, pulses of light race through thin glass threads to carry internet and phone calls across the state in a fraction of a second.

Waves with short wavelengths carry much more energy, so they can change or damage living cells. Ultraviolet light is used to sterilize, meaning to kill germs, on hospital tools and in drinking water systems. X-rays pass through soft skin but not bone, so doctors use them to photograph fractures. Gamma rays, the most energetic of all, are aimed at tumors in radiation therapy. Telescopes collect many of these waves from space, letting astronomers study stars they could never visit.

Try it: Would a doctor choose radio waves or X-rays to check for a broken arm, and why?