- Radiation is emitted by all charged particles undergoing acceleration.
- All radiation involves electromagnetic waves.
- Radiation transmits energy.
- The spectrum represents the range of possible frequencies or wavelengths of the radiation.
Because of the random nature of the vibrations over a large number of particles, the emitted radiation will have a range of frequencies, or wavelengths. Statistical analysis shows that in an ideal situation the energy emitted at any one wavelength is a function of that wavelength. This is known as Planck’s Law and is shown graphically below for a range of temperatures. The radiation emitted in this ideal situation is known as Blackbody radiation, which simply means that it has the distribution pattern that would be expected from a perfect emitter in thermal equilibrium. (Diagram source: Wikipedia ‘blackbody‘ article)