Question

Many bicycles have generators that have a light that can be powered without a battery. Instead of a battery, a magnet and a coil of wire are used to make an electric current flow. The setup shown below models how a bicycle generator functions to produce light. Currently, no electric current is flowing through the circuit shown.



What needs to happen to cause an electric current to flow through the circuit?
A.
A bigger light bulb needs to be used.
B.
The magnet's north pole needs to point up.
C.
The magnet needs to be in constant motion.
D.
A smaller wire needs to be used.

Answer 1

C. The magnet needs to be in constant motion.

Explanation: A changing magnetic flux through the coil (caused by moving the magnet relative to the coil) induces a voltage and thus a current (Faraday's law). A stationary magnet or a fixed orientation produces no changing flux, so no current flows.