What is radiant energy primarily defined as?

Radiant energy is primarily defined as energy that is emitted, transferred, or received in the form of electromagnetic radiation. This definition encompasses any form of energy that moves through space as electromagnetic waves, such as visible light, infrared, and ultraviolet radiation. Focusing on the energy aspect highlights the inherent properties of various forms of radiation and their interactions with matter.

Power and energy are related but distinct concepts; power refers to the rate at which energy is transferred or converted, whereas energy itself represents the capacity to do work. Therefore, while it is accurate to discuss power in relation to radiant energy, the primary focus of the definition is on the energy itself rather than the rate of energy transfer or the measurement units involved.

In contrast, the other choices introduce measurements or focus on power, which, while relevant to discussions about energy, do not capture the breadth of what radiant energy entails as purely energy in various forms. The focus on "energy" rather than "power" in the correct choice aligns with the fundamental principles of physics regarding energy transfer and interaction with the environment.