Physics

29. Which of Earth's geographic poles is nearest its magnetic north pole? a. South Pole b. North Pole c. both A and B

a. South Pole

8. If a magnet is pushed into a coil, voltage is induced across the coil. If the same magnet is pushed into a coil with a greater speed a. a larger voltage is induced. b. a smaller voltage is induced. c. the same voltage is induced.

a. a larger voltage is induced.

23. A wire carrying a current is bent into a loop. The magnetic field is strongest a. at the center of the loop. b. at the edges of the loop. c. where the loop is located.

a. at the center of the loop.

____ 16. If you break a bar magnet in half, each half a. becomes a bar magnet with two poles. b. becomes unmagnetized. c. contains one magnetic pole.

a. becomes a bar magnet with two poles.

37. A bar magnet is falling through a loop of wire with constant velocity. The north pole enters first. As the south pole leaves the loop of wire, the induced current (as viewed from above) will be: a. clockwise. b. counterclockwise. c. zero. d. along the length of the magnet.

a. clockwise.

4. The phenomenon of inducing voltage by changing the magnetic field around a conductor is called a. electromagnetic induction. b. generated voltage. c. Faraday's induction. d. electromagnetic radiation. e. transformer induction.

a. electromagnetic induction.

17. If you put a small compass in a magnetic field, the compass will a. line up in a direction parallel to the magnetic field lines. b. swing randomly. c. line up in a direction perpendicular to the magnetic field lines. d. seek electrical charge concentrations

a. line up in a direction parallel to the magnetic field lines.

18. Magnetic field strength is a. strongest close to a magnet. b. constant everywhere around a magnet. c. strongest far from a magnet.

a. line up in a direction parallel to the magnetic field lines.

9. The principal reason voltage is induced in the loops of a generator coil is that the a. loops are rotating, changing the amount of magnetic field within the loops. b. size of the loops is changing. c. magnet's strength is changing. d. magnet is rotating. e. all of the above

a. loops are rotating, changing the amount of magnetic field within the loops.

12. The source of all magnetism is a. moving electric charges. b. ferromagnetic materials. c. tiny domains of aligned atoms. d. tiny pieces of iron. e. none of the above

a. moving electric charges.

33. A uniform 4.5-T magnetic field passes perpendicularly through the plane of a wire loop 0.10 m 2 in area. What flux passes through the loop? a. 5.0 Tm 2 b. 0.45 Tm 2 c. 0.25 Tm 2 d. 0.135 Tm 2

b. 0.45 Tm

6. A generator is used to light a bulb. Energy for lighting the bulb actually comes from a. a plug where the generator is connected to the wall. b. a mechanical input to the generator. c. the magnet in the generator. d. the coil of wire. e. none of the above

b. a mechanical input to the generator.

15. If the north pole of one magnet is brought near the south pole of another magnet, the poles will a. repel each other. b. attract each other. c. not interact with each other at

b. attract each other.

____ 24. In order to make an electromagnet, you need a a. battery, a nail, and a magnet. b. battery, some wire, and a nail. c. loop of wire, contacts, and a battery. d. magnet, a nail, and some wires. e. none of the above

b. battery, some wire, and a nail.

26. Loops of wire in a motor rotate because a a. battery effectively pushes a loop around in the field. b. current exerts a force on the loop, causing it to rotate. c. magnetic field exerts forces on moving electrons in the loop. d. magnet attracts stationary electrons in the wire. e. none of the above

b. current exerts a force on the loop, causing it to rotate.

A magnet is moved in and out of a coil of wire connected to a high-resistance voltmeter. If the number of coils doubles, the induced voltage a. is the same. b. doubles. c. quadruples. d. halves. e. none of the above

b. doubles.

31. Magnetic field lines surrounding a magnet are conventionally drawn a. from south to north. b. from north to south. c. either way.

b. from north to south.

35. A bar magnet is falling through a loop of wire with constant velocity. The south pole enters first. As the magnet leaves the wire, the induced current (as viewed from above): a. is clockwise. b. is counterclockwise. c. is zero. d. is along the length of the magnet.

b. is counterclockwise.

28. The force on an electron moving in a magnetic field will be the largest when its direction a. is at an angle other than 90 degrees to the magnetic field direction. b. is perpendicular to the magnetic field direction. c. is the same as the magnetic field direction. d. is exactly opposite to the magnetic field direction. e. none of the above ____

b. is perpendicular to the magnetic field direction.

27. The discrepancy between the orientation of a compass and true north is known as the a. radioactive effect. b. magnetic declination. c. magnetic effect. d. none of the above.

b. magnetic declination.

Electric current can best be induced in a wire by a. stretching the wire. b. moving a magnet up and down near the wire. c. setting the wire near a magnet. d. rotating the wire. e. none of the above

b. moving a magnet up and down near the wire.

21. The reason a magnet can attract an unmagnetized nail is that a. nails really are magnetized. b. nails become temporarily magnetized in a magnetic field. c. nails become permanently magnetized in a magnetic field. d. a magnet can attract any metal object.

b. nails become temporarily magnetized in a magnetic field.

30. Which pole of a compass needle points to a south pole of a magnet? a. south pole b. north pole c. both A and B

b. north pole

11. An electric motor and an electric generator are a. entirely different devices. b. very similar devices. ___

b. very similar devices.

36. A coil is placed in a changing magnetic field and an emf is induced. What happens to the induced emf if the rate of change of magnetic field quadruples? a. There is no change. b. The emf doubles. c. The emf quadruples. d. The emf increases by a factor of 16.

c. The emf quadruples.

. A device consisting of a coil that is mechanically rotated in a stationary magnetic field is called a. a motor. b. a magnetic pole. c. a generator. d. a transformer. e. a dipole.

c. a generator.

14. Surrounding every moving electron is a. an electric field. b. a magnetic field. c. both A and B d. none of the above

c. both A and B

25. A galvanometer can also be made into a. an ammeter. b. a voltmeter. c. both A and B d. none of the above

c. both A and B

Changing the magnetic field intensity in a closed loop of wires induces a. current. b. voltage. c. both current and voltage. d. neither current nor voltage.

c. both current and voltage.

19. Magnetic domains are a. regions that may or may not be magnetized. b. clusters of atoms randomly aligned. c. regions of atoms magnetically aligned. d. blocks of material.

c. regions of atoms magnetically aligned.

32. In physics lab, you hang a wire perpendicular to the magnetic field created by a horseshoe magnet. You observe that the wire moves downward when you allow current to flow through it. What happens when you reverse the direction of current? a. The wire moves toward the North pole of the magnet. b. The wire moves toward the South pole of the magnet. c. The wire moves further downward. d. The wire moves upward.

d. The wire moves upward.

20. Permanent magnets can be made by a. placing a piece of iron near a strong electromagnet. b. placing a piece of iron in a strong magnetic field. c. stroking material containing iron with a magnet. d. all of the above e. none of the above ____

d. all of the above

10. In an electromagnetic wave, the electric and magnetic fields are _____ to each other and _____ to the direction of wave motion. a. opposite, parallel b. at right angles, perpendicular c. parallel, at right angles d. at right angles, parallel

d. at right angles, parallel

7. A device that transforms electrical energy to mechanical energy is a a. generator. b. transformer. c. magnet. d. motor. e. none of the above

d. motor.

34. According to Lenz's law the direction of an induced current in a conductor will be that which tends to produce which of the following effects? a. enhance the effect which produces it b. produce a greater heating effect c. produce the greatest voltage d. oppose the effect which produces it

d. oppose the effect which produces it

13. An iron rod becomes magnetic when a. positive charges line up on one side and negative charges on the other side. b. positive ions gather at one end and negative ions at the other end. c. its electrons stop moving and point in the same direction. d. the net spins of its electrons point in the same direction. e. none of the above

d. the net spins of its electrons point in the same direction.

22. When current passes through a wire, a magnetic field is created around the wire only if the a. wire is absolutely straight. b. wire is curved in a loop. c. current makes a complete loop. d. current comes from a battery. e. A magnetic field is always created around the wire.

e. A magnetic field is always created around the wire.