Question

Which change will cause an increase in the electric current produced through electromagnetic induction?

using more wire loops in the solenoid
using the opposite pole of the magnet
using a weaker magnet
moving the solenoid

Answer 1

The changes that will increase the induced current are:
- using more wire loops in the solenoid
- moving the solenoid (so the magnetic flux through it changes faster)

Why: Faraday’s law: emf = −N dΦ/dt. Increasing N (more turns) or increasing the rate of flux change (moving the solenoid relative to the magnet) raises the induced emf and so (for a given circuit resistance) the current. Using the opposite pole only reverses the sign (direction) of the induced current, and using a weaker magnet reduces the flux and so lowers the induced emf/current.

Note: in a real coil adding turns also increases its resistance, so the net current change depends on both the increased emf and the increased resistance.