8.2.1 Force on a Current Carrying Conductor in a Magnetic Field

1. We have learned that when current flows in a conductor, a magnetic field will be generated.
2. When the current-carrying conductor is placed in a magnetic field, the interaction between the two magnetic fields will produce a resultant field known as the catapult field as shown in the figure below.
   
   
3. The catapult field is a non-uniform field where the field at one side is stronger than the other side.
4. As a result, a force is produced to move the current carrying conductor from the stronger field to the weaker field.
5. The force produced by a catapult field is called the catapult force.
6. The direction of the force can be determined by Fleming's left hand rule as shown in Figure below.
   
7. The fore finger, middle finger and the thumb are perpendicularly to each other. The forefinger points along the direction of the magnetic field, middle finger points in the current direction and the thumb points along the direction of the force.
8. The strength of the force can be increased by:
   1. Increase the current
   2. Using a stronger magnet
   3. using a longer wire
   4. arranging the wire perpendicular to the direction of the magnetic field.

Force between 2 Current-Carrying Conductors

1. When 2 current carrying conductors are placed close to each other, a force will be generated between them.
2. If the current in both conductors flow in the same direction, they will attract each other, whereas if the current are in opposite direction, they will repel each other.
3. This force is due to the interaction between the magnetic field of the 2 conductor.
4. The figure below shows the catapult field produced by 2 current carrying conductors when their current is in the same direction or opposite direction.

(Magnetic field generated when 2 current carrying conductors with currents move in the same direction are brought close to each other. The field will cause the 2 conductors attract each other)

(Magnetic field generated when 2 current carrying conductors with currents move in the opposite direction are brought close to each other. The field will cause the 2 conductors repel each other)