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

In the sketch of the magnetic field around a bar magnet, you should show the bar magnet with its North (N) and South (S) poles labeled. Draw two field lines emerging from the North pole and curving around to the South pole, indicating the direction of the magnetic field lines which move from North to South.

To demonstrate this, set up a circuit that includes a power supply, a voltage source, a conductor (like a straight wire), and a magnet.

1. Connect the components in series, ensuring the conductor is positioned within the magnetic field created by the magnet.
2. Turn on the power supply to allow current to flow through the conductor.
3. Observe the conductor; you should notice it being deflected or moving, indicating that it experiences a force due to the interaction with the magnetic field.

1. The strength of the magnetic field (B)
2. The current flowing through the conductor (I)
   The force also depends on the length of the conductor that is within the magnetic field and the angle at which the conductor interacts with the field.

When the magnet is moved towards the coil, an induced current is detected in the coil, as indicated by the deflection of the galvanometer. This shows that an electromotive force (emf) is generated due to the change in magnetic flux.

This occurs due to electromagnetic induction, where the movement of the magnet changes the magnetic field around the coil, inducing a current according to Faraday's law of electromagnetic induction. The change in magnetic flux through the coil induces an electromotive force (emf) in the coil.

When the speed of the magnet is increased, the induced emf and, consequently, the current will also increase. This is because a faster movement of the magnet leads to a greater rate of change of the magnetic flux through the coil, increasing the induced current observed on the galvanometer.

One application of this effect is in the operation of electrical generators, where mechanical energy is converted to electrical energy through electromagnetic induction, or in devices like induction cookers which utilize this principle for efficient heating.