Question

In principle, we can generate an electric current by moving a coil of wire back and forth near a magnet. However, in a practical electric generator, we supply mechanical energy by rotating a coil. Using moving contacts, we can connect the ends of the coil to an external wire to complete the circuit. A current then flows through the circuit. The mechanical energy we supply to the generator is ____.

a. Transformed to heat
b. Transformed to potential energy
c. Transformed to electrical energy
d. Conserved in the system

Answer 1

The mechanical energy supplied to a generator is transformed to electrical energy, according to the principles of electromagnetic induction.

Step-by-step explanation:

When mechanical energy is supplied to an electric generator, such as by rotating a coil in the presence of a magnetic field, the mechanical energy is not conserved within the system, nor transformed to heat or potential energy in the context of energy conversion by the generator. Instead, it is transformed to electrical energy. The principle behind this transformation is Faraday's law of electromagnetic induction, which states that a changing magnetic environment of a coil of wire induces an electromotive force (EMF) in the coil. A practical electric generator often consists of loops of wire in a magnetic field, with some external mechanical force—like falling water, steam from burned fossil fuels, or wind—causing the rotation. This rotation in the magnetic field induces an alternating current (AC) in the wire, which is then used as electrical energy.