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ELECTROMAGNETISM TEST

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
 

1. 
The region around a magnet in which magnetic forces can act is called the
a.
magnetic field.
c.
pole.
b.
domain.
d.
solenoid.
 

2. 
What do you end up with if you cut a magnet in half?
a.
one north-pole piece and one south-pole piece
b.
two unmagnetized pieces
c.
two pieces, each with a north pole and a south pole
d.
two north-pole pieces
 

3. 
The magnetic effects of a bar magnet are strongest near the ____.
a.
center
c.
ends
b.
top
d.
bottom
 

4. 
Any material that attracts iron or materials containing iron is called a
a.
solenoid.
c.
superconductor.
b.
magnet.
d.
semiconductor.
 

5. 
The magnetic effects of a bar magnet are
a.
evenly distributed throughout a magnet.
b.
distributed randomly in a magnet.
c.
concentrated near the ends.
d.
None of the above
 

6. 
Sometimes the magnetic strip on a credit card becomes demagnetized. This strip is most likely a(n)
a.
permanent magnet.
c.
electromagnet.
b.
temporary magnet.
d.
geomagnet.
 

7. 
If you attach a magnet to a string so that the magnet is free to rotate, you will see that one end of the magnet will point
a.
north.
c.
east.
b.
southwest.
d.
west.
 

8. 
A compass needle is
a.
a fixed magnet.
b.
a fixed nonmagnetic piece of metal.
c.
a magnet that is free to rotate.
d.
a nonmagnetic piece of metal that is free to rotate.
 

9. 
Magnetic poles always occur
a.
alone.
c.
in threes.
b.
in pairs.
d.
in fours.
 

10. 
The magnetic force will push magnets apart if you hold the
a.
north poles of two magnets close together.
b.
south poles of two magnets close together.
c.
north pole of one magnet near the south pole of another magnet.
d.
Both (a) and (b)
 

11. 
Magnetic poles are similar to electric charges in that
a.
like poles repel and opposite poles attract.
b.
the magnetic force is equal to the electric force.
c.
the number of magnetic domains responsible for the poles is conserved.
d.
the mass of the magnetized particle is conserved.
 

12. 
The magnetic field around a bar magnet can be modeled by drawing
a.
curved lines from the north pole of the magnet to the south pole.
b.
curved lines near the south pole of the magnet.
c.
straight lines from the north pole and from the south pole.
d.
circular lines around the entire magnet.
 

13. 
Whether a material is magnetic depends on the ____ in the material.
a.
molecules
c.
number of neutrons
b.
atoms
d.
number of protons
 

14. 
What makes materials magnetic?
a.
The atoms in these materials are magnetized by moving electrons.
b.
The atoms in these materials are randomly arranged.
c.
The atoms in a domain are arranged so that the north and south poles of all the atoms line up.
d.
All of the above
 

15. 
Permanent magnets
a.
cannot lose their magnetization.
c.
have randomly oriented domains.
b.
are difficult to magnetize.
d.
are easy to magnetize.
 

16. 
An electric fan has an electric motor inside to change
a.
kinetic energy into electrical energy.
c.
electrical energy into thermal energy.
b.
thermal energy into electrical energy.
d.
electrical energy into kinetic energy.
 

17. 
____ discovered the relationship between electricity and magnetism.
a.
William Gilbert
c.
Joseph Henry
b.
Michael Faraday
d.
Hans Christian Oersted
 

18. 
Four solenoids have the same number of loops. Which solenoid would produce the strongest magnetic field?
a.
the solenoid with 1 A of current
c.
the solenoid with 10 A of current
b.
the solenoid with 100 A of current
d.
the solenoid with 0.1 A of current
 

19. 
Electric motors work by placing a(n) ____ between the poles of a permanent magnet or an electromagnet.
a.
armature
c.
galvanometer
b.
electromagnet
d.
Both (a) and (b)
 

20. 
A device that uses electromagnetic induction to convert kinetic energy into electrical energy is called a(n)
a.
transformer.
c.
commutator.
b.
generator.
d.
armature.
 

21. 
What would induce a greater electric current in a wire?
a.
adding more loops of wire
b.
removing loops of wire
c.
pulling the magnet out rather than pushing it in
d.
pushing the magnet in rather than pulling it out
 

22. 
If each of the following solenoids carries the same electric current, which one would produce the strongest magnetic field?
a.
a solenoid with a single loop
c.
a solenoid with 100 loops
b.
a solenoid with 10 loops
d.
a solenoid with 1,000 loops
 
 
Examine the magnetic field lines around the magnets below, and answer the questions that follow:

electricity_files/i0240000.jpg
 

23. 
Which magnet is the strongest?
a.
Magnet A
c.
Magnet C
b.
Magnet B
d.
All magnets have the same strength.
 

24. 
Which magnet is the weakest?
a.
Magnet A
c.
Magnet C
b.
Magnet B
d.
All magnets have the same strength.
 
 
The diagrams below illustrate magnetic domains within two metallic substances. Unshaded areas correspond to one type of pole, and darkly shaded areas correspond to the opposite type of pole.

electricity_files/i0270000.jpg
 

25. 
Which substance is magnetized?
a.
A
c.
Both A and B
b.
B
d.
Neither A nor B
 

Completion
Complete each sentence or statement.
 

26. 
All magnets have two ____________________ where the magnetic effects are strongest.
(poles or inductors)
 

 

27. 
Within an object are tiny magnetic ____________________ that can be either aligned or misaligned. (remains or domains)
 

 

28. 
____________________ magnets retain their magnetic properties well but are difficult to magnetize. (Temporary or Permanent)
 

 

29. 
A(n) ____________________ converts kinetic energy into electrical energy. (electric motor or generator)
 

 

30. 
The interaction between electricity and magnetism is called ____________________. (electromagnetism or electromagnetic induction)
 

 

31. 
An ____________________ changes electrical energy into kinetic energy. (electric motor or electromagnet)
 

 

32. 
A(n) ____________________ is a coil of wire that produces a magnetic field when it is carrying an electric current. (solenoid or electric motor)
 

 

33. 
Electric motors use ____________________ current.
 

 

34. 
A loop or coil of wire that rotates in an electric motor is a(n) ____________________.
 

 

35. 
A device used to measure current through the interaction of an electromagnet and a permanent magnet is called a(n) ____________________.
 

 

EXTRA CREDIT
 

36. 
Name three properties of magnets.
 

37. 
Suppose you have two bar magnets. One has its north and south poles marked, but the other one does not. Describe how you could use the first magnet to identify the poles of the second magnet.
 

38. 
Name the metals used to make ferromagnets.
 

39. 
How are temporary magnets different from permanent magnets?
 

40. 
Why are auroras more commonly seen in places like Alaska and Australia than in places like Florida and Mexico?
 



 
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