Question

Which ray exists beyond the red end of the visible spectrum in an electromagnetic spectrum? State its properties, uses and detection method (one each).

Answer 1

The radiation that exists just beyond the red end of the visible spectrum is Infrared radiation (or Infrared rays).

• Property: They have a strong heating effect (thermal effect) because they are easily absorbed by the molecules of a substance, which increases its temperature.
• Use: They are widely used in TV remote controls and other wireless short-range communication systems.
• Detection Method: They can be detected using a thermopile (or a sensitive thermometer with a blackened bulb), which shows a rapid rise in temperature when exposed to infrared rays.