Question

Given below is a circuit to study the magnetic effect of electric current. ABCD is a cardboard kept perpendicular to the conductor XY. A magnetic compass is placed at the point P of the cardboard. P1 and P2 are the positions of the magnetic compass, before and after passing a current through XY respectively.

1. Name the rule that is used to predict the direction of deflection of the magnetic compass.
2. State the direction of current in the conductor (X to Y or Y to X) when the circuit is complete.
3. If resistance R is increased, then what will be the effect on the magnetic lines of force around the conductor?

Answer 1

1. Right hand thumb rule.
2. Since the compass is pointing west, the current will flow from X to Y in an anticlockwise direction.
3. The amount of current flowing through the circuit will decrease if the resistance increases. The magnetic field then decreases as the magnetic lines of force surrounding the conductor grow less dense.