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Lesson: Chapter 4 — Waves and their applications

4.2.2. Uses of electromagnetic waves 4 of 5

Infrared radiation

Below red in frequency, and invisible to us, lies infrared. Hot objects give it out, and we feel it as warmth on the skin — so it is often called heat radiation.

Our own bodies give out infrared. Thermal images made from it can help find some diseases, and infrared cameras let people and animals be watched at night.

Figure to be added

Figure 4.17 — a thermal image of a hand, the warmest parts shown red and yellow.

Remote controls

Remote controls send their signals to a television as infrared.

Cameras

Many cameras in mobile phones and computers are sensitive to infrared.

Physiotherapy

Infrared is used in physiotherapy treatments.

Night vision

Infrared binoculars and cameras show people and animals in the dark.

Figure to be added

Figure 4.18 — (a) a remote control pointed at a television; (b) an infrared camera.