. 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 I flows in P (as seen by E) and an induced current IQ1 flows in Q. The switch remains closed for a long time. When S is opened, a current IQ2  flows in Q. Then the directions of IQ1 and IQ2 (as seen by E) are     


A. Respectively clockwise and anticlockwise

B. Both clockwise

C. Both anticlockwise 

D. Respectively anticlockwise and clockwise

Best Answer

Ans: D

Sol: When switch S is closed magnetic field lines passing through Q increases in the direction from right to left. So, according to Lenz’s law induced current in Q i.e. IQ1  will flow in such a direction so that the magnetic field lines due to IQ2 passes from left to right through Q. This is possible when IQ1  flows in anticlockwise direction as seen by E. Opposite is the case when switch S is opened i.e. IQ2 will be clockwise as seen by E.

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