Electro Magnetic Induction And Alternating Currents Question 324

Question: As , P and Q are two coaxial conducting loops separated by some distance. When the switch S is closed, a clockwise current $ I_{P} $ flows in P (as seen by E) and an induced current $ {I_{Q_{1}}} $ flows in Q. The switch remains closed for a long time. When S is opened, a current $ {I_{Q_{2}}} $ flows in Q. Then the directions of $ {I_{Q_{1}}} $ and $ {I_{Q_{2}}} $ (as seen by E) are [IIT JEE (Screening) 2002]

Options:

A) Respectively clockwise and anticlockwise

B) Both clockwise

C) Both anticlockwise

D) Respectively anticlockwise and clockwise

Show Answer

Answer:

Correct Answer: D

Solution:

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.  $ {I_{Q_{1}}} $  will flow in such a direction so that the magnetic field lines due to  $ {I_{Q_{2}}} $ passes from left to right through Q. 

This is possible when  $ {I_{Q_{1}}} $  flows in anticlockwise direction as seen by E. 

Opposite is the case when switch S is opened i.e.  $ {I_{Q_{2}}} $ will be clockwise as seen by E.


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