As shown in the figure, P and Q are two coaxial conducting loops separated by some distance. When the switch S is closed, a clockwise current flows in P (as seen by E) and an induced current flows in Q. The switch remains closed for a long time. When S is opened, a current flows in Q. Then the direction of and (as seen by E) are [2002]

(4)
When switch is closed, a magnetic field is set up in the space around . The field lines threading increase in the direction from right to left. According to Lenz's law, will flow so as to oppose the cause or change and flow in the anticlockwise direction as seen by . Opposite is the case when is opened. will be clockwise.