Force Acting on a Current Carrying Wire
A current carrying wire of length L in a magnetic field B experiences a force F given
F is the force exerted on the wire, i is the current in the wire and B is the force all represented by vectors. Hence the force is given by the cross product of vectors i and B multiplied by the length of the wire.
Example 1In the figure below, a magnetic field B out of the page exerts a force F (downward) on the current directed to the left. Again the right hand rule was used to find the direction of F as follows:
- Point the index finger in the direction of the current i
- Point the middle finger in the direction of the magnetic field B
and the thumb gives the direction of the force F.
Example 2A wire of length 150 cm carrying an electric current of 0.1 A in the negative x direction and perpendicular to a magnetic field B, experiences a force of 6.0 × 10-3 N in the positive y direction due to a magnetic field. Find a) the magnitude and b) direction of the magnetic field.