Electric Fields
Practice Test
1.
A 75-kg rock climber first climbs 25 m to the top of a quarry, then descends 75 m from the top to the bottom of the quarry. If the initial height is the reference level, what is the potential energy of the system (climber plus Earth) at the top?
a.
1.8×10
4
J
b.
-3.7×10
4
J
c.
-1.8×10
4
J
d.
3.7×10
4
J
Hint
2.
If the charge of an atom's nucleus is +2 and the charge of the surrounding electrons is -2, the atom is __________.
a.
electrically neutral
b.
unstable
c.
positively-charged
d.
negatively-charged
Hint
3.
If 2.0×10
2
J of work are performed to move one coulomb of charge from a positive plate to a negative plate, what potential difference exists between the plates?
a.
5.0×10
-3
V
b.
2.0×10
3
V
c.
1.6×10
-19
V
d.
2.0×10
2
V
Hint
4.
In the set-up of Figure 21-9, if the electric force up on a drop equals the gravitational force down on the drop, the drop ___.
a.
will accelerate down
b.
could move upward at constant speed
c.
will accelerate up
d.
must be stationary
Hint
5.
The superposition of waves with equal but opposite amplitueds causes __________.
a.
constructive interference
b.
dissidence
c.
destructive interference
d.
consonance
Hint
6.
If no other forms of energy besides kinetic and gravitational potential energy are present, then mechanical energy is represented by the equation __________.
a.
PE
g
=
E
+
KE
b.
M
E
= 1/2 (
KE
)(
PE
g
)
2
c.
PE
g
=
mgh
d.
E
=
KE
+
PE
g
Hint
7.
In Figure 11-12, if cart D were given an initial velocity of 1 m/s to the left, what would the final velocities of each cart be?
a.
cart C, 1 m/s to the left; cart D, 1 m/s to the right
b.
cart C, 0 m/s; cart D, 2 m/s to the right
c.
cart C, 0 m/s; cart D, 0 m/s
d.
cart C, 2 m/s to the left; cart D, 1 m/s to the left
Hint
8.
The __________ is the position at which gravitational potential energy is zero.
a.
initial position
b.
reference level
c.
height
d.
release point
Hint
9.
In Figure 14-2, if the scale of the graph is 1 block = 10 N on the vertical axis and one block = 2 cm on the horizontal axis, what is the spring constant?
a.
20 N/m
b.
500 N/m
c.
5 N/m
d.
250 N/m
Hint
10.
If a charge were added to Figure 20-11b between the two charges already there, what direction would the net force on it be?
a.
To the right, regardless of its sign
b.
To the right if charge is positive, to the left if it's negative.
c.
This cannot be determined without knowing more about the location of the charge
d.
To the left if charge is positive, to the right if it's negative.
Hint
11.
What does a wave carry?
a.
particles
b.
heat
c.
energy
d.
matter
Hint
12.
Amorphous solids have no __________.
a.
shape
b.
crystalline pattern
c.
liquid phase
d.
volume
Hint
13.
In Figure 14-1, if the spring's constant is 20.0 N/m and x has a value of 0.25 m, what is m equal to?
a.
0.63 kg
b.
0.06 kg
c.
0.51 kg
d.
5.0 kg
Hint
14.
What happens to a bimetallic strip when it is heated?
a.
it contracts
b.
it bends
c.
its cohesive properties decrease
d.
it becomes elastic
Hint
15.
A standing wave appears to be __________.
a.
fluctuating
b.
standing still
c.
moving very slowly
d.
moving very fast
Hint
16.
Materials through which electrical charges will not move easily are called __________.
a.
conductors
b.
grounders
c.
ions
d.
insulators
Hint
17.
How far apart are a proton and an electron if they exert a force of attraction of 4.5 N on each other?
a.
1.8 × 10
-5
m
b.
1.6 × 10
-19
m
c.
9.6 × 10
-15
m
d.
7.2 × 10
-15
m
Hint
18.
An electric field is about 150 N/C downward. What is the direction of the force on a positively-charged particle?
a.
downward
b.
upward
c.
stationary
d.
changes rapidly
Hint
19.
A positive test charge of 9.0 × 10
-5
" to "9.0×10
-5
C is in an electric field that exerts a force of 3.7×10
-5
N on it. What is the magnitude of the electric field at the location of the test charge?
a.
0.41 N/C
b.
0.24 N/C
c.
2.4 N/C
d.
4.1 N/C
Hint
20.
In Figure 14-14, how do the frequencies of the waves in pictures a and c compare?
a.
a's frequency is twice c's.
b.
a's frequency is four times c's.
c.
a's frequency is half of c's.
d.
a's frequency is one-quarter of c's.
Hint
