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.
