Theory of Radiation-Optical Spectrum. Electromagnetic radiation is energy that doesnot need a medium of transmission and can bepropagated even in vacuum. There are manykinds of sources or radiators of electromagneticenergy.
Thermal radiators emit electromagneticradiation by virtue of their temperature.
Incandescent lamps are thermal radiators andtheir operation can be best explained in termsof the laws of thermal radiation. Most of theenergy from thermal radiators is distributedbetween the area of macrowaves and the farend of ultra-violet radiation. Incandescent Lamps as Energy Radiators Tungsten wire, used in incandescent lampsacts as thermal radiator emitting energy mostlyin the near infrared region from 300-5000nanometers. Tungsteen is capable of supporting temperatures of up to 3650 K thus becoming the best known source of thermal energythat can be harnessed in small vacuum or inertgas filled glass tubes. Figure 2 shows therelative energy distribution of miniatureincandescent lamps.