Physics 12 Unit: Electromagnetism Worksheet

Physics 12

Unit: Electromagnetism Worksheet.

Name:_____________________

1) Several paper clips dangle from the north pole of a magnet. The induced pole in the bottom of the lowermost paper clip is a a. north pole.

b. south pole.

c. north or south pole-no difference really.

2) Magnetic field lines about a current-carrying wire a. extend radially from the wire. c. both of these

b. circle the wire in closed loops. d. neither of these

3) When there is a change in the magnetic field in a closed loop of wire, a. a voltage is induced in the wire. c. electromagnetic induction occurs. e. none of these

b. current is made to flow in the loop of wire. d. all of these

4) Thrust a magnet into a coil of wire and the coil a. becomes an electromagnet. c. both of these

b. has a current in it. d. neither of these

5) When a magnet is thrust into a coil of wire, the coil tends to a. attract the magnet as it enters. c. both of these

b. repel the magnet as it enters. d. neither of these

6) Electromagnetic induction occurs in a coil when there is a change in a. electric field intensity in the coil. b. magnetic field intensity in the coil. c. voltage in the coil. d. the coil's polarity. e. electromagnetic polarity.

7) Voltage can be induced in a wire by a. moving the wire near a magnet. c. changing the current in a nearby wire. e. none of these

b. moving a magnet near the wire. d. all of these

8) The magnetic field strength inside a current-carrying coil will be greater if the coil encloses a a. vacuum. d. rod of iron.

b. wooden rod. e. none of these

c. glass rod.

9) If a magnet is pushed into a coil, voltage is induced across the coil. If the same magnet is pushed into a coil with twice the number of loops, a. one-half as much voltage is induced. b. the same voltage is induced. c. twice as much voltage is induced. d. four times as much voltage is induced. e. none of these 10) A device that transforms electrical energy to mechanical energy is a a. generator. d. magnet.

b. motor. e. none of these

c. transformer.

11) A step-up transformer increases a. power.

b. energy.

c. both of these

d. neither of these

12) Changing the magnetic field intensity in a closed loop of wires induces a. current.

b. voltage.

c. both of these

d. neither of these

13) A step-up transformer has a ratio of 1 to 10. Neglecting slight losses, if 100 W of power go into the primary coil, the power corning from the secondary coil is a. 1 W.

b. 10 W.

c. 100 W.

d. 1000 W.

e. none of these

14) The voltage across the input terminals of a transformer is 110 V. The primary has 50 loops and the secondary has 25 loops. The voltage the transformer puts out is a. 25 V.

b. 55 V.

c. 110 V.

d. 220 V.

e. none of these

15) A certain transformer doubles input voltage. If the primary coil has 10 A of current, then the current in the secondary coil is a. 2 A.

b. 5 A.

c. 10 A.

d. 25 A.

e. none of these

16) As a motor armature turns faster and faster, net current in the motor windings a. increases.

b. decreases.

c. remains unchanged.

17) What is the main difference between electric charges and magnetic poles? a. electric charges can be isolated, magnetic poles cannot be isolated b. electric charges cannot be isolated, magnetic poles can be isolated c. electric charges both attract and repel, magnetic poles only attract d. electric charges both attract and repel, magnetic poles only repel e. magnetic poles both attract and repel, electric charges only repel