Question

A 10-turn coil of wire having a diameter of 1.0 cm and a resistance of 0.60? is in a 1.0 mT magnetic field, with the coil oriented for maximum flux. The coil is connected to an uncharged 3.0?F capacitor rather than to a current meter. The coil is quickly pulled out of the magnetic field.

A) Afterward, what is the voltage across the capacitor?

Answer 1

induced emf is induced in the coil when the coil is pulled out (in delta t time) of magnetic field (B1=1 milli Tesla) to that of B2 (=0)

induced emf = - delta (phi)/delta (t) = NA[B1-B2]/delta (t)
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flux is maximum when B vector and coil area vector are parallel
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current (I) = e/R = NA[B1-B2] / R*delta (t)
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hete delta (t) is the time (quickly) during which coil was pulled out, and during which I flowed in associated circuit with capacitor and R. coil Area A = 1 cm^2 = 10^-4 m^2

charge stored Q = I * delta (t)
Q = {NA[B1-B2] / R*delta (t) } *delta (t)
Q = NA[B1-B2] / R
Q = 10*[10^-4 m^2] [(1 - 0)*10^-3 Tesla] / 20 ohm
Q = 5 *10^-8 coulomb