What are the properties of thermal radiation?
Answers
Thermal radiation is electromagnetic radiationgenerated by the thermal motion of particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation. Particle motion results in charge-acceleration or dipole oscillation which produces electromagnetic radiation.
The infrared radiation emitted by animals that is detectable with an infrared camera, and the cosmic microwave background radiation, are all examples of thermal radiation.
If a radiation-emitting object meets the physical characteristics of a black body in thermodynamic equilibrium, the radiation is called blackbody radiation.[1] Planck's law describes the spectrum of blackbody radiation, which depends solely on the object's temperature. Wien's displacement lawdetermines the most likely frequency of the emitted radiation, and the Stefan–Boltzmann law gives the radiant intensity.[2]
Thermal radiation is also one of the fundamental mechanisms of heat transfer.
Answer:
Radiation is the mode of heat transfer or in general,
energy transfer by electromagnetic waves/quanta.
Thermal radiation or heat radiation is the radiation
produced by thermal agitation of the particles ofa
body, and its spectrum, ie., frequency distribution
or wavelength distribution, is continuous from the far infrared to the extreme ultraviolet region
depending on the temperature of the body.
Properties
(1) Thermal radiations are electromagnetic waves/
quanta extending from the far infrared to the ex
treme ultraviolet region. In this spectrum, the in-
frared waves (wavelengths ranging from about 700
nm to about 1 mm) are sensed as heat.
(2) They have the same speed in free space as that of
light, nearly 3 x 10 m/s, which makes radia-tion
the most rapid mode of heat transfer
(3) They exhibit all the optical phenomena of light, viz,
reflection, absorption, refraction, interference, dif-
fraction and polarization.
(4) Radiation incident on a body is, in general, partly
reflected, partly absorbed and partly transmitted.
(5) Thermal radiation obeys the inverse-square law of
intensity, ie., the intensity at a point is inversely
proportional to the square of its distance from a
point source of radiation.