5 Radiation and Electromagnetic Spectrum Radiation is emitted by everything that has an absolute temperature greater than 0 deg C and is transferred as a series of waves. The energy contained in the wave is released when absorbed by an object. These waves consist of an electrical and magnetic component and thus called electromagnetic waves. The quantity and quality of this radiation is described by the amplitude and the wavelength of the electromagnetic waves.
All objects radiate in many wavelengths.
The electromagnetic spectrum radiated by the sun has a maximum wavelength of 0.5 microns, whereas the maximum wavelength emitted by the earth is 10 microns. The most intense wavelength emitted by an object is determined by its temperature . This relationship is known as Wien s Law. Wien s law shows that as the temperature of an object increases, the maximum wavelength of the radiated energy decreases. Because the maximum wavelength emitted by the sun is longer than that emitted by the earth, radiation emitted by the sun is often called shortwave radiation, whereas radiation emitted by the earth is called longwave radiation.