The magnetic field at one place on the earth\'s surface is 55 T in strength and

Question

The magnetic field at one place on the earth's surface is 55 T in strength and tilted 60 down from horizontal. A 170-turn coil having a diameter of 3.5 cm and a resistance of 2.20 is connected to a 1.40 F capacitor rather than to a current meter. The coil is held in a horizontal plane and the capacitor is discharged. Then the coil is quickly rotated 180 so that the side that had been facing up is now facing down.

Afterward, what is the voltage across the capacitor?
Hint: Use I=dq/dt to relate the net change of flux to the amount of charge that flows to the capacitor.

Express your answer to two significant figures and include the appropriate units.

Explanation / Answer

induced emf = - delta (phi)/delta (t) = NB delta[A - A1] /delta (t) * Cos(60)

E = - 2*170*55*10^-6*pi*(0.0175)^2 * Cos(60)

E = 8.995*10^-6 V
------------------------
current (I) = E/R = 8.995*10^-6 / 2.2 = 4.08*10^-6 A
charge stored Q = I * delta (t)
Q = 4.08*10^-6 coulomb
V = Q/C = 4.08*10^-6 / 1.4*10^-6

V = 2.91 V

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