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MHT CET202523 Apr 2025Evening ShiftPhysicsElectromagnetic InductionActual

A coil of ' n ' turns and area ' A ' is suddenly removed from a magnetic field, a charge ' q ' flows through the coil. If resistance of the coil is ' R ' then the magnetic flux density is (in Wb / m ^2 )

Options

  1. Aq^2 R 2 n A
  2. BqR nA
  3. CqR ^2 nA
  4. DqR 2 nA

Correct answer

B. qR nA

Step-by-step solution

The induced charge flow results from the change in magnetic flux linkage through the coil as it is removed from the field. The initial magnetic flux linkage is _i = nBA , assuming perpendicular orientation. After removal, _f = 0 , giving a total flux change = -nBA . By Faraday's law, the induced EMF is = - d dt , so the current becomes I = R = - 1 R d dt . The total charge transferred during the process is q = I dt = - 1 R _ _i ^ _f d = - 1 R ( _f - _i) = nBA R . Solving for B yields B = qR nA . This corresponds to

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