Margaret Scott, age 16, of Annapolis, Md., for her question:

WHAT IS LENTS LAW?

Lenz's law is a principle of physics that is important in the design of electric generators. It was developed by a German born scientist named Heinrich F.E. Lenz who worked in Russia.

Lenz's law says that in an electric generator, the current produced creates a magnetic field that opposes the action of the force that produces the current.

In other words, work must be done to generate electricity.

Powerful turbines are needed to run generators that supply large amounts of current. According to Lenz's law, the magnetic field can be used as a "brake" to slow down the generating mechanism.