Section 25.1
Magnets: Electric Current from Changing Magnetic Fields
Practice Test
1.
What does
EMF
not depend upon?
a.
velocity of wire
b.
length of wire
c.
composition of wire
d.
magnetic field
Hint
2.
A 120-W lightbulb is placed across a generator with
I
max
of 0.650 A. If the maximum voltage of the generator is 150.0 V, what is the resistance of the bulb?
a.
326 Ω
b.
231 Ω
c.
163 Ω
d.
116 Ω
Hint
3.
What is the unit for
EMF
?
a.
V
b.
N
c.
C/J
d.
N·m
Hint
4.
A current __________ in a stationary wire in an unchanging magnetic field.
a.
cannot exist
b.
is not produced
c.
always exists
d.
is easily generated
Hint
5.
A changing magnetic field can produce a(n)__________.
a.
resistor
b.
spark of electricity
c.
force
d.
electric current
Hint
6.
Effective current and voltage relate to __________.
a.
alternating current
b.
average resistance
c.
magnetic fields
d.
equivalent resistance
Hint
7.
A wire is moving toward you through a magnetic field directed to your right. In what direction is the force?
a.
to the right
b.
toward you
c.
downward
d.
upward
Hint
8.
In Figure 25-2, if the wire were moved to the left instead of the right, what would the direction of the magnetic force on it be?
a.
down
b.
into the page
c.
out of the page
d.
up
Hint
9.
In Figure 25-2, if the north and south poles were switched, what would the direction of the magnetic force on the wire be?
a.
out of the page
b.
down
c.
into the page
d.
up
Hint
10.
A wire 15 m long moves through a magentic field of 1.0 T. The wire moves at a constant speed of 5.7 m/s in a direction perpendicular to the magnetic field. What
EMF
is induced in the wire?
a.
61 V
b.
43 V
c.
2.6 V
d.
86 V
Hint
11.
An electric generator converts __________.
a.
electrical energy into mechanical energy
b.
electrical energy into magnetic energy
c.
mechanical energy into electrical energy
d.
magnetic energy into electrical energy
Hint
12.
Electromotive force is the same as __________.
a.
current
b.
potential difference
c.
magnetic flux
d.
resistance
Hint
13.
You want to generate an
EMF
of 2.6 V by moving a wire at 3.0 m/s through a 0.040-T magnetic field. If you keep the wire perpendicular to the magnetic field, what length of wire should you use?
a.
11 m
b.
0.035 m
c.
0.046 m
d.
22 m
Hint
14.
An AC generator produces a maximum voltage of 512 V and a maximum current of 0.80 A. What is the effective voltage and effective current of the generator?
a.
362 V, 0.57 A
b.
724 V, 0.57 A
c.
362 V, 1.13 A
d.
724 V, 1.13 A
Hint
15.
If the average power dissipated by an electric light is 75 W, what is the maximum power?
a.
100 W
b.
150 W
c.
75 W
d.
50 W
Hint
16.
__________ is the generation of current due to relative motion between a wire and a magnetic field.
a.
Electrolysis
b.
Magnetic flux
c.
Electromagnetic induction
d.
Electrospectrometry
Hint
17.
A 0.30-m long straight wire moves at a constant speed of 9.5 m/s perpendicular to a magnetic field of strength 0.083 T. What
EMF
is induced in the wire?
a.
0.24 V
b.
2.6 V
c.
1.2 V
d.
0.48 V
Hint
