A magnetic field exists in the vicinity of a magnet - Leaving Cert Physics - Question 9 - 2009

1. Apparatus: Use a U-shaped magnet and a supply of iron filings.

2. Procedure: Place a piece of paper or cardboard over the magnet. Sprinkle iron filings evenly on the surface. Gently tap the paper to allow the filings to align along the magnetic field lines.

3. Observation: Note the resulting pattern formed by the iron filings, which illustrates the magnetic field lines extending from the poles of the U-shaped magnet.

4. Diagram: Include a diagram depicting the setup and the resulting pattern of filings.

When the switch is closed, an electric current flows through the wire, generating a magnetic field around the wire. The compass needle will deflect from its original position due to this induced magnetic field, aligning itself with the direction of the magnetic field produced by the current.

This shows that an electric current creates a magnetic field in its vicinity, indicating the interrelationship between electricity and magnetism. This effect is fundamental to electromagnetic principles.

When the switch is opened, the electric current stops flowing. Consequently, the magnetic field around the wire disappears, and the compass needle returns to its original position, indicating the absence of the induced magnetic field.

When a current flows through the wire placed between the poles of a U-shaped magnet, the wire experiences a force. This force acts in a direction determined by the right-hand rule, causing the wire to move either up or down depending on the direction of the current relative to the magnetic field.

If the current flows in the opposite direction, the direction of the force acting on the wire will also reverse, leading to movement in the opposite direction.

Two devices that utilize this effect are:

1. Electric motor
2. Galvanometer