Energy conversion. Illustration of examples of energy changing from one form into another. An car engine converts energy (chemical to mechanical), as do a thermonuclear reaction (nuclear to thermal and radiation energy), photosynthesis (light to chemical energy), an electric mixer (electrical to mechanical energy), a hammer (mechanical to heat, sound and deformation energy), and a lamp (electrical to heat and light). The law of conservation of energy states that energy can neither be created nor destroyed, but it can transform from one form to another.