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Electromagnetic induction occurs in a coil, when

• a magnetic flux is produced in a coil.

• a magnetic flux through the coil is changing with time.

• an emf is induced in a coil, which has magnetic flux.

• a current is induced in the coil, which has magnetic flux.

A current of 10.0 A is flowing through an inductor with self inductance 5 mH. The energy stored in the magnetic field produced by the current is

• 0.21 J

• 0.35 J

• 0.50 J

• 0.25 J

Faraday’s law states that the induced emf in a coil is directly proportional to

• the rate of change in the magnetic flux.

• the rate of change in the electric flux.

• the rate of change in the electric field.

• the rate of change in the magnetic field.

A coil lies flat on a level table top in a region where the magnetic field vector points straight up. The magnetic field suddenly grows stronger. When viewed from above, what is the direction of the induced current in this coil as the field increases?

• Counterclockwise

• Clockwise

• Clockwise initially, then counterclockwise before stopping

• There is no induced current in this coil.

A flux of 4.0 × 10-5 Wb is maintained through a coil for 0.50 s. What emf is induced in this coil by this flux?

• 8.0 × 10-5 V

• 4.0 × 10-5 V

• 2.0 × 10-5 V

• No emf is induced in this coil.

A circular loop of radius 0.10 m is rotating in a uniform magnetic field of 0.20 T. Find the magnetic flux through the loop when the plane of the loop and the magnetic field vector are parallel.

• zero

• 3.1 × 10-3 Wb

• 5.5 × 10-3 Wb

• 6.3 × 10-3 Wb

A bar magnet is dropped from above and falls through the loop of wire shown in figure. The north pole of the bar magnet points downward towards the page as it falls. Which statement is correct?

• The current in the loop always flows in a clockwise direction.

• The current in the loop always flows in a counterclockwise direction.

• The current in the loop flows first in a clockwise, then in a counterclockwise direction.

• The current in the loop flows first in a counterclockwise, then in a clockwise direction.

A wire moves across a magnetic field. The emf produced in the wire depends on

• the strength of the magnetic field.

• the length of the wire.

• the orientation of the wire with respect to the magnetic field vector.

• all of the given answers

A bar (L = 80 cm) moves on two frictionless rails, as shown, in a region where the magnetic field is uniform (B = 0.30 T) and into the paper. If v = 50 cm/s and R = 60 mΩ, what is the magnetic force on the moving bar?

• 0.48 N to the right

• 0.48 N to the left

• 0.32 N to the left

• 0.32 N to the right

The current flowing in a coil changes at a rate of 4 A in 0.02 seconds. If the back-emf in the coil is 3.0 V, what is the self-inductance of the coil?

• 0.010 H

• 0.015 H

• 0.020 H

• 0.025 H