Question

Nolan set up the equipment shown in order to induce a current in a wire.

A horizontal coil of wire on a spool is connected to 2 terminals of a meter with a needle, which can go from plus to minus. A hand holds a bar magnet oriented horizontally near the right end of the spool with the S pole toward the spool and the N pole toward the hand.

Which best explains why no current is induced?

The wire needs to be coiled less tightly.
The wire needs to be straight, not coiled.
The magnet needs to be moved through the coils of wire.
The magnet needs to be held above the coils of wire.

Answer 1

The magnet must be moved through (or toward/away from) the coils of wire.

Reason: Faraday’s law — an emf (current) is induced only when the magnetic flux through the coil changes. Holding the magnet stationary produces no change in flux, so no current. Moving the magnet into or out of the coil changes the flux and induces a current.