Electromagnetic Induction 3

1. A bar magnet is dropped through a solenoid, as shown.

What is the direction of the induced current in the solenoid as the magnet enters the top (i) and as the magnet leaves the bottom (ii)?

2.

A coil of 150 turns and an area of 2.0 ´10-4 m2 is placed in a 1.00 T magnetic field as shown in Diagram I.

If this field changes to 0.45 T in 0.060 s, what is the average emf induced in the coil and in what direction does the induced current flow?

3. Two solenoids S1 and S2 are placed close together as shown in the diagram below.

Immediately after the switch is closed, what is the direction of current flow through galvanometer G and what is the direction of the magnetic field produced by this current at position P inside solenoid S2?

4. A magnet is moved towards an aluminum ring suspended on string as shown.

Determine the direction in which current will flow in the ring and the direction in which the ring will move.

5.

A flexible loop of wire of area 4.5 ´ 10-2 m2 is positioned in a 0.17 T magnetic field as shown in Figure A. The loop is then stretched until its area is zero in a time of 0.35 s (Figure B). What is the average induced emf in the circuit and the direction of the current through resistor R?

6.

A loop of wire of area 0.32 m2 is placed in a 0.75 T magnetic field as shown. The magnetic field is changed to 0.35 T in the opposite direction in 0. 45 s.

What are the magnitude and direction of the current through the 15 W resistor?

7.

A coil of copper wire is wrapped around a compass as shown. Which way will the compass needle point when current flows through the coil?

A. W                                         B. X                                       C. Y                                       D. Z

8.

One hundred turns of wire are wrapped around an iron core with a cross-sectional area of 0.0015  m2 . The ends of the wire are connected to a resistor producing a circuit with a total resistance of 10.0 W.

If the magnetic field in the iron core changes from 3.0 T towards the left to 1.0 T towards the right, how much charge flows in the circuit?

 A. 0.030 C B. 0.060 C C. 0.30 C D. 0.60 C
9.

The single rectangular loop shown below is being pulled into the magnetic field at 2.0 m/s. Determine the emf developed in the loop.

 A. 0.017 V B. 0.11 V C. 0.21 V D. 0.64 V

10.

A circular loop of resistance 1.2 W is pulled a distance of 0.40 m into a perpendicular magnetic field as shown below.

An average current of 0.50 A is produced in the coil during this event. Calculate the constant speed with which the coil was pulled.

A. 0.10 m/s

B. 0.75 m/s

C. 1.9 m/s

D. 2. 4 m/s

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