1. A permanent magnet is held directly below the center of a coil which is conne

Question

1. A permanent magnet is held directly below the center of a coil which is connected to a voltmeter. As you move the magnet farther away from the coil, the voltmeter reads negative. Which of the following statements is always true?

The farther away from the coil the magnet is held in place, the lower the magnitude of the voltage.

Moving the magnet closer towards the coil would also produce a negative voltage reading.

If you had turned the magnet around so that "South" would be on top, then moving it farther away from the coil would still produce a negative voltage readout.

Moving the magnet to the left would produce a positive voltage readout.

Moving the magnet to the right would produce a negative voltage readout.

Twisting the magnet clockwise about its long axis would produce a positive voltage readout.

2. The coil has a radius of 4 cm and 110 turns. While moving the magnet farther away from the coil, at a certain point in time, the voltage meter shows -330 mV. What is the magnitude of the rate of change of the flux through the coil?

Explanation / Answer

1.
The farther away from the coil the magnet is held in place, the lower the magnitude of the voltage. this is always true

----------------

2. induced emf e = N AdB/dt

AdB/dt = rate of change of magnetic flux

so

magnitude of change of magnetic flux = -330e-3/(110) = 3 milli Wb

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