What is a magnetic field? Draw a sketch of the magnetic field around a bar magnet - Leaving Cert Physics - Question 9 - 2005

A sketch of the magnetic field around a bar magnet includes:

• A diagram showing a bar magnet labeled with 'N' for north and 'S' for south.
• Field lines starting from the north pole, curving around to the south pole, densely packed around the poles and spaced further apart away from the magnet, indicating the strength of the field.

1. Apparatus: Use a power supply, conductor (wire), and a magnet.
2. Procedure: Set up the circuit by connecting the power supply to the conductor, ensuring it's in a magnetic field created by the magnet.
3. Observation: When current flows through the conductor in the magnetic field, it experiences a force and moves. This movement can be observed as the conductor deflecting from its original position.

1. The strength of the magnetic field: A stronger magnetic field increases the force.
2. The amount of current flowing through the conductor: More current results in a greater force.

When the magnet is moved towards the coil, the galvanometer shows a deflection, indicating that a current is being induced in the coil.

This occurs due to electromagnetic induction, which is the phenomenon where a changing magnetic field within a closed loop induces an electromotive force (emf) in the wire, causing a current to flow.

When the speed of the magnet's movement is increased, the rate of change of the magnetic field through the coil increases, resulting in a larger induced current. Consequently, the galvanometer's needle deflects more significantly.

One application of electromagnetic induction is in electric generators, where mechanical energy is converted into electrical energy using rotating coils within a magnetic field.