What quantity is called the flux density of electromagnetic radiation?

The radiation flux density is equal to the product of the electromagnetic energy density and the velocity of its propagation. The density of the radiation flux is determined by the energy transferred in time through the surface of a unit area in the direction perpendicular to this surface.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.