A wire carrying a current will experience a force in the presence of a magnetic field. This is known as the motor effect.
A current-carrying wire produces its own magnetic field, as does a permanent magnet. This means that if we place the wire (or coil) between the north and south poles of two permanent magnets, then the two magnetic fields will interact.
The interaction between the two magnetic fields will result in a force on the wire, pushing it out of the field. This force will be at a right angle to both the direction of the wire carrying current and the direction of the magnetic field.
However, to experience the full force, the wire has to be at exactly 90 degrees (right angle) to the magnetic field. This means that if the wire is at a different angle, it will experience less force. If the wire is going in the same direction as the field, then the wire will experience no force.
To find the direction of the force, we need to know:
To understand how the two factors affect the force, we can use a concept called Fleming’s left-hand rule.
Using your left hand, this rule involves:
To calculate the magnitude of the force acting on a current-carrying wire placed at a right angle to the direction of a magnetic field, we use the following equation:
Magnetic flux density is a measure of the strength of the magnetic field.
4 A of current flows through a 20 cm length of wire. The wire is placed at a right angle in a 0.6 T magnetic field. Calculate the force acting on the wire.