Explain an activity to show that a current-carrying conductor experiences a force when placed in a magnetic field.

Explanation

A current-carrying conductor experiences a magnetic force due to a magnetic field. The force is maximum when the conductor is placed perpendicular to the direction of magnetic field. To demonstrate the force we perform the following experiment:
Experiment: Take a small sized aluminium rod AB of length about 5 cm. Suspend the rod AB horizontally from a rigid stand using two connecting wires.
Place a strong horse-shoe magnet NS in such a way that the rod AB lies between the poles of the magnet. Let the north pole N of magnet lies below the rod and the south pole S lies above the rod as shown in Fig. 13.27. Thus, a magnetic field directed in vertically upward direction is present.

Complete the electrical circuit of aluminium rod AB by connecting it in series with a battery , Key K and a variable resistance .
Put the in key K so that an eletric current begins to flow through the aluminium rod from end B to end A . We observe that on passing current the rod AB is displaced towards the left . It showns that the aluminium rod is experiencing a mechanical force due to which it is being deflected . Direction of deflection is given by Fleming.s left hand rule .
Effect of change in direction of current : Reverse the connections of battery so that on applying plug in Key K , current flows , in the aluminium rod from A to B. We now find the rod AB is deflected toward the right. Thu s, by reversing the direction of current , direction of force is also reversed . It is accordance with Fleming.s left - hand rule .
Effect of change in direction of magnetic field : Now reverse the direction of magnetic field to vertically downward direction. For this purpose suspend , the horse - shoe magnet in such a way that N-pole of magnet lies above the aluminium rod AB and S -pole of magnet lies below the rod . It now current in aluminium rod is flowing from A to B , then the rod is flowing from A to B , then the rod is deflected towards let . It show that direction of deflection (or the direction of force) is reversed on reversing the direction of magnetic field .