Infrared (IR) radiation is a type of electromagnetic radiation with wavelengths longer than visible red light but shorter than microwaves — roughly 750 nanometers (nm) to 1 millimeter (mm).
Key points about infrared radiation:
- Position in the spectrum
- Lies just beyond the red end of the visible spectrum.
- Has lower frequency and lower photon energy than visible light.
- Heat connection
- Often associated with heat, because warm objects (including people) emit IR radiation naturally.
- This is why infrared cameras can “see” in the dark by detecting heat patterns.
- Subdivisions
- Near-infrared (NIR): Closest to visible light; used in fiber optics and remote controls.
- Mid-infrared (MIR): Used in thermal imaging and environmental monitoring.
- Far-infrared (FIR): Associated strongly with thermal radiation from objects.
- Interactions with matter
- Readily absorbed by water and many organic molecules, making it useful in spectroscopy to study materials.
- Applications
- Night vision devices, TV remotes, thermal imaging, weather forecasting, astronomy, and medical diagnostics.