Lenz's Law and Conservation of Energy

Vocabulary terms and definitions explaining how the law of conservation of energy justifies Lenz's law and the conversion of mechanical energy to Joule heat.

Lenz's law

A principle stating that when a magnet is moved either towards or away from a coil, the induced current produced opposes its motion.

Resisting force

The opposing force exerted on a moving magnet by the induced current, requiring work to be done by an external agency to maintain motion.

Mechanical energy of the moving magnet

The energy expended by an external agency to move a magnet against a resisting force, which is converted into electrical energy in the coil.

Joule heat

The form of thermal energy in the coil into which the induced electrical energy is ultimately converted.

Perpetual motion machine

An impossible machine that moves without any expense of energy, which would hypothetically arise if the induced current helped rather than opposed the motion of the magnet.

Law of conservation of energy

The fundamental physical law that establishes the truth of Lenz's law by demonstrating that energy is converted from one form to another rather than created without expense.