# Joint Entrance Examination/2000 Screening/Q029 Coil of wire with conducting ring at centre and variable current

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# Original Question by Dharav talk

Here's the question...
 A coil of wire having finite inductance and resistance has a conducting ring placed co-axially within it. The coil is connected to a battery at time t = 0, so that a time dependent current I1(t) starts flowing through the coil. If I2(t) is the current induced in the ring, and B (t) is the magnetic field at the axis of the coil ,due to 11(t) then as a function of time (t > 0), the product I2(t)B(t) (A) increases with time (B) decreases with time (C) does not vary with time (D) passes through a maximumPosted by Dharav talk 14:11, 17 August 2009 (UTC)

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