Photochemistry is the study of chemical reactions, isomerization, and physical behavior that can occur when exposed to visible and/or ultraviolet light. Understanding photochemical reactions is based on two key principles:
The first law of photochemistry states that for a photochemical reaction to occur, light must be absorbed by the component.
According to the second law of photochemistry, each photon of light absorbed by a chemical system activates just one molecule for further reaction. Albert Einstein developed the quantum (photon) theory of light and came up with this "photo equivalence law."
Photobiology is a wide term that encompasses all biological processes that include non-ionizing radiation. Photobiological responses are known to be the outcome of chemical and/or physical changes in biological systems induced by non-ionizing radiation. Photophysics, photomovement, photosynthesis, photochemistry, photomorphogenesis, visual processing, circadian rhythms, bioluminescence, and ultraviolet radiation effects are all studied in this field.
The study of chemical reactions that cause electrons to move is known as electrochemistry. It is a sub-discipline of physical chemistry concerned with the relationship between electrical potential as a quantifiable and quantitative phenomena and identifiable chemical change, with electrical potential as an outcome of a specific chemical change or vice versa. The movement of electrons is known as electricity, and it can be generated by moving electrons from one element to another in an oxidation-reduction ("redox") reaction.