Electromagnetic Induction
Practice Test
1.
What is a superconductor?
a.
a magnet
b.
a meterial with a very high resistance
c.
a powerful battery
d.
a material with zero resistance
Hint
2.
Lines drawn to represent an electric field extend __________ a positive charge and __________ a negative charge.
a.
away from, toward
b.
away from, away from
c.
toward, toward
d.
toward, away from
Hint
3.
In Figure 21-7b, if both charges were 7.0
μ
C and the left charge were held in place while the right charge were moved from a separation of 0.4 m" to "0.40 m, how much work would be done on the system?
a.
-2.2 J
b.
2.2 J
c.
1.1 J
d.
-1.1 J
Hint
4.
A transformer goes from 10 V to 5000 V. How do the number of loops relate in the different coils?
a.
There are 500 times more loops in the primary coil.
b.
There are 5000 times more loops in the primary coil.
c.
There are 500 times more loops in the secondary coil.
d.
There are 50 times more loops in the secondary coil.
Hint
5.
Coulomb's law states that __________.
a.
the magnitude of the force between two charges is inversely proportional to the magnitude of the charges and proportional to the square of the distance between them
b.
the direction of the magnetic field in a wire is perpendicular to the flow of electric current in the wire
c.
the ratio of the potential difference to the current is constant
d.
the magnitude of the force between two charges is proportional to the magnitude of the charges and inversely proportional to the square of the distance between them
Hint
6.
Two parallel plates are given opposite charges. A voltmeter measures the electric potential difference to be 47.0 V. The plates are 5.0 cm apart. What is the magnitude of the electric field between them?
a.
1.1×10
-4
N/C
b.
9.4×10
3
N/C
c.
9.4×10
2
N/C
d.
1.1×10
-3
N/C
Hint
7.
A wire is moving toward you through a magnetic field directed to your right. In what direction is the force?
a.
toward you
b.
downward
c.
upward
d.
to the right
Hint
8.
The best explanation for why the phenomenon in Figure 20-1 occurs is ____.
a.
the opposite electrical charges on the ruler and paper bits are attracted to each other.
b.
the paper bits are gravitationally attracted to the ruler.
c.
the same electrical charges on the ruler and paper bits are attracted to each other.
d.
the paper bits are magnetically attracted to the ruler.
Hint
9.
If the ammeter in Figure 22-3 were moved to the left of the light bulb, what would it read?
a.
2 A
b.
4 A
c.
1 A
d.
0 A
Hint
10.
A south pole will __________ another south pole.
a.
attract
b.
destroy
c.
ignore
d.
repel
Hint
11.
In Figure 24-16, if the magnetic poles were reversed, what would the direction of the magnetic force be?
a.
left
b.
up
c.
right
d.
down
Hint
12.
Materials that allow charges to move about easily are called __________.
a.
plastics
b.
conductors
c.
facilitators
d.
insulators
Hint
13.
What is the unit for
EMF
?
a.
C/J
b.
N
c.
N·m
d.
V
Hint
14.
A 12.0 V battery delivers a 1.20 A current to an electric motor that is connected across terminals. What power is consumed by the motor?
a.
14.4 J
b.
14.4 W
c.
10.0 J
d.
10.0 W
Hint
15.
If the combined resistance of the potentiometer and motor in Figure 22-5 is 250 Ω, what is the current through the circuit?
a.
3000 A
b.
21 A
c.
48 mA
d.
120 A
Hint
16.
An electric field is about 150 N/C downward. What is the direction of the force on a positively-charged particle?
a.
changes rapidly
b.
downward
c.
upward
d.
stationary
Hint
17.
A force of -7.7×10
3
N exists between a positive charge of 5.6×10
-4
C and a negative charge of -2.1×10
-4
C. What distance separates the charges?
a.
3.7 m
b.
0.14 m
c.
1.4 m
d.
0.37 m
Hint
18.
A step-up transformer has 400 turns on its primary coil and 1000 turns on its secondary coil. If the secondary coil has a current of 1.30 A, what is the current in the primary coil?
a.
7.75 A
b.
0.520 A
c.
3.25 A
d.
1.62 A
Hint
19.
The second right hand rule is used to determine the __________.
a.
amount of current
b.
direction of magnetic force
c.
direction of the magnetic field
d.
direction of current
Hint
20.
A 10-m long wire carrying 5 A of current is at right angles to a uniform magnetic field of 0.01 T. What is the magnitude of the force on the wire?
a.
0.5 N
b.
0.05 N
c.
5 N
d.
50 N
Hint
