Question

Yoon Ki investigates electromagnetic induction by moving a bar magnet into a coil of wire. His experimental setup is shown.

A coil or loop of wire is held horizontally and connected to a galvanometer measuring current. A hand holds a bar magnet and moves it into the coil.

What change would most improve his results?

moving the magnet faster
using more loops of wire in the coil
using the south pole of the magnet
connecting the galvanometer to the coil

Answer 1

Using more loops of wire in the coil.

Reason: Faraday’s law gives emf = −N dΦ/dt, so increasing the number of turns N increases the induced emf (and current) for the same motion. Moving the magnet faster also helps (increases dΦ/dt), but adding turns is a more effective and reliable way to boost the signal. Using the south pole only reverses the current direction, and the galvanometer is already connected.