Section 24.1
Magnets: Permanent and Temporary
Practice Test
1.
How can you make a magnet out of a long strand of wire and an iron bar?
a.
Attach the wire to either end of the bar, and send a current through it.
b.
Spin the bar over the wire as a current runs through it.
c.
Send a current through the bar.
d.
Wrap the wire around the bar, and send a current through it.
Hint
2.
If current is reduced in an electromagnet, what happens to the magnetic field strength?
a.
it increases
b.
it disappears completely
c.
it remains the same
d.
it is reduced
Hint
3.
According to geologic evidence, Earth's magnetic poles __________.
a.
have switched over the years
b.
have only recently appeared
c.
are a constant force on the planet
d.
have remained the same
Hint
4.
A nail that touches a magnet will __________.
a.
generate an electric current
b.
become polarized
c.
demagnetize the magnet
d.
melt
Hint
5.
The ___________ is proportional to the strength of the magnetic field.
a.
size of the magnet
b.
magnetic flux
c.
mass of the magnet
d.
magnetic flux per unit area
Hint
6.
What happens if you cut a magnet in half?
a.
it becomes demagnetized
b.
you get a separate south pole and a separate north pole
c.
you get monopoles
d.
you get two magnets
Hint
7.
Magnetic domains are __________ in a magnet.
a.
scattered
b.
random
c.
aligned
d.
misaligned
Hint
8.
Which of the following phenomena is NOT illustrated in Figure 24-9?
a.
In space, magnetic field lines point from north to south.
b.
A current causes a magnetic field.
c.
Magnetic field lines form closed loops.
d.
The magnetic field caused by a wire is stronger closer to the wire.
Hint
9.
A south pole will __________ another south pole.
a.
ignore
b.
attract
c.
destroy
d.
repel
Hint
10.
In Figure 24-7, if somehow the poles on the middle magnet could suddenly be reversed, which of the following would NOT happen?
a.
The middle magnet would stick to the one below it.
b.
The middle magnet would stick to the one above it.
c.
The bottom magnet would stick to the one above it.
d.
The top magnet would fall slightly.
Hint
11.
The second right hand rule is used to determine the __________.
a.
direction of magnetic force
b.
amount of current
c.
direction of the magnetic field
d.
direction of current
Hint
12.
Magnetic field lines travel from __________.
a.
in a circle around the entire magnet, while never touching the magnet
b.
north pole to south pole outside the magnet
c.
north pole to south pole through the magnet
d.
south pole to north pole outside the magnet
Hint
