Infra red absorption

Infrared radiation lies between the visible and microwave portions of the electromagnetic spectrum. Infrared waves have wavelengths longer than visible and shorter than microwaves, and have frequencies which are lower than visible and higher than microwaves.

The primary source of infrared radiation is heat. This is the radiation produced by the motion of atoms and molecules in an object. The higher the temperature, the more the atoms and molecules move and the more infrared radiation they produce. Any object which has a temperature anything above absolute zero (-273.15 oC or 0 K), radiates in the infrared. In above experiment iron radiates heat and the black bootle absorbing more heat than the white bottle. As a result pressure increases in black container and liquid in pipe is moving to container with lower pressure (white bottle).

Our eyes are detectors which are designed to detect visible light waves which are one of the few types of radiation that can penetrate our atmosphere and be detected on the Earth's surface. The electromagnetic spectrum includes gamma rays, X-rays, ultraviolet, visible, infrared, microwaves, and radio waves. The only difference between these different types of radiation is their wavelength or frequency.