Cracking the SAT Physics Subject Test

constant—that is, it will be conserved. For example, electrical energy can be
converted into light and heat (this is how a light bulb works), but the amount of
electrical energy coming into the lightbulb equals the total amount of light and heat
given off. Energy cannot be created or destroyed; it can only be transferred (from
one system to another) or transformed (from one form to another).