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Question: Answered & Verified by Expert
A very long solenoid of radius R is carrying current It=kte-αtk>0, as a function of time t0. Counterclockwise current is taken to be positive. A circular conducting coil of radius 2R is placed in the equitorial plane of the solenoid and concentric with the solenoid. The current induced in the outer coil is correctly depicted, as a function of time, by:
PhysicsMagnetic Effects of CurrentJEE MainJEE Main 2019 (09 Apr Shift 2)
Options:
  • A
  • B
  • C
  • D
Solution:
2544 Upvotes Verified Answer
The correct answer is:
ϕouter=μ0nKte-αt4πR2
ε=-dϕdt=-μ0nK4πR2(e-αt1-αt)
iinduced=-ce-αt1-αtResistance
At t=0, Iinduced=-ve
From the above equation and initial value of current we can say the correct graph is B.

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