Infrared Waves

What Are Infrared Waves?

Infrared waves are electromagnetic waves with frequencies and wavelengths that place them just below the visible spectrum — specifically, at its low-frequency (long-wavelength) end. They are produced by hot bodies and molecules that vibrate or rotate.

Why Are They Called "Heat Waves"?

Most materials contain water molecules, which strongly absorb infrared radiation. Other molecules like CO₂ and NH₃ also absorb it. When absorbed, the molecules' thermal motion increases — they heat up and transfer that heat to their surroundings. This is why infrared waves are often referred to as heat waves.

Key Physical Effects and Applications

• Physical therapy: Infrared lamps deliver heat to sore muscles and joints.
• Greenhouse effect: Incoming visible light from the Sun passes through the atmosphere, is absorbed by Earth's surface, and is re-radiated as infrared radiation (longer wavelength). Greenhouse gases (CO₂, water vapour) trap this radiation, maintaining Earth's average temperature. …