A current flowing through a conductor creates a magnetic field around it - Leaving Cert Physics - Question 10 - 2021

To demonstrate the magnetic field around a current-carrying conductor, follow these steps:

1. Apparatus: Gather materials including a straight piece of conductor (like a wire), a DC power supply, a compass, and a sheet of paper.

2. Method: Place the straight conductor horizontally on the table. Connect the ends of the wire to the power supply. Position the compass at various points around the conductor, ensuring the compass needle can move freely.

3. Observation: Once the current is turned on, observe the direction in which the needle of the compass aligns itself. It will deflect from its north orientation, indicating the presence and direction of the magnetic field created by the current in the wire.

The shape of the magnetic field around a straight conductor is circular. To draw it:

• Indicate the wire in the center.
• Draw concentric circles around the wire to represent the magnetic field lines.
• Use arrows on the circles to show the direction of the magnetic field, which is determined by the right-hand rule (curl the fingers of your right hand around the wire in the direction of current flow; your thumb points in the direction of the magnetic field).

The magnitude of the force experienced by a current-carrying conductor in a magnetic field depends on:

1. Magnetic flux density (B): The strength of the magnetic field.
2. Current (I): The amount of electric current flowing through the conductor.
3. Length of the conductor (L): The length of the conductor that is within the magnetic field.

The force F acting on a charge q moving at a velocity v in a magnetic field of flux density B is given by the equation:

$F = qvB$
Where:

• F is the force (in Newtons),
• q is the charge (in Coulombs),
• v is the velocity (in m/s),
• B is the magnetic flux density (in Tesla).
  This equation assumes that the velocity is perpendicular to the magnetic field.