Changing magnetic field causes current
A solenoid is connected in series to a galvanometer as shown below.
A galvanometer measures both the magnitude and the direction of a current.
A bar magnet is moved in and out of the solenoid.
This is the set-up of Faraday's experiment on electromagnetic induction.
- Current flows when the bar magnet is moving into the solenoid or out of the solenoid.
- Current is zero when the magnet is stationary.
- A potential difference (electromotive force) is induced whenever the magnetic field passing through the solenoid changes. This causes a current to flow, which is detected by the galvanometer.