Faraday's Law

Faraday's Law

In his experiment in 1831, he noticed that when he moved a permanent magnet in and out of a coil or loop of wire, it induced an electromotive force or emf, in other words a voltage, and therefore a current was produced.

Michael Faraday

He discovered the faraday's law

law of electromagnetic induction

Whenever there is a change in the magnetic flux relative to the coil, an electromotive force is induced.

law of electromagnetic induction

The magnitude of the induced electromotiveforce is directly proportional to the rate ofchange of the magnetic flux linked with thecoil.

magnetic flux

the amount of magnetic field lines through a given conductor

changing magnetic flux

The change in magnetic field in the coil can be quantified as

Strength the magnet

Increasing the strength of the magnet will increase change in magnetic flux and also the magnitude of the induced emf and induced current.

Increasing the motion of the magnet

As the speed of the magnet increases as it moves through the coil, the magnitude of the induced emf and induced current also increases.

The number of turns of the coil

Increasing the number of turns of the coil will also increase the magnitude of the induced emf and induced current.

decreases

When the speed of the magnet decreases as it moves towards a coil, the magnitude of the induced current also \___________.

increases; increases

If the strength of a magnet \_________,the magnitude of induced current \_______.

D

Electromotive force can be induced by\____.
A. Moving a magnet near a wire
B. Moving the wire near the magnet
C. Changing magnetic field in a near by wire
D. All of these

C

Which of the statements is true when there is change in magnetic field in a closed loop of wire.
A. There is no current induced in the wire
B. The induced current is free to move in any direction of the wire
C. Electromotive force is induced in the wire
D. All of these

D

Which of the following is NOT a way that a magnetic field can be varied to induce a current in a wire?
A. Rotate the coil inside the magnetic field
B. Move the coil in and out the magnetic field
C. Change the strength of the magnetic field
D. Move the coil out of the magnetic field

When the north pole of the magnet is moved towards the loop or coil, the pointer of the galvanometer deflects towards the right. The direction of the induced current is opposite the movement of the magnet.

When the magnet is at rest, the galvanometer shows zero reading. There is no current induced at this time. This proves that as long as the magnet keeps moving, current flows in the coil.

If the magnet is moved away from the coil, the induced current flows to the direction opposite the movement of the magnet. Thus, the galvanometer deflects towards the left