Formulae for the radiant energy of electromagnetic waves and Planck's law of radiation.
Numerical example of Planck’s radiation formula:
The sun has a surface temperature of 5,800 K; the associated radiant power according to Planck’s radiation formula is 3.85 x 1023 kW. Only a very small proportion of this strikes the earth (with vertical radiation incidence 1.37 kW/m²).
Information and ideas:
Radiant energy can be converted into other energy forms. In the case of an X-ray radiograph the radiant energy is converted into chemical energy (blackening of the photo film), light is converted into electrical energy in a solar cell, and similarly radio waves in an antenna. The energy of microwaves can be used for heating food.