Current Electricity
Practice Test
1.
In an accident on a slippery road, a car with mass 800.0 kg, moving at 12.0 m/s, smashes into the rear end of a car with mass 1250 kg moving at 8.0 m/s in the same direction. How much kinetic energy was lost in the collision if the wrecked cars lock together?
a.
3.9×10
4
J
b.
4.1×10
4
J
c.
3.9×10
3
J
d.
6.1×10
4
J
Hint
2.
Materials through which electrical charges will not move easily are called __________.
a.
grounders
b.
conductors
c.
insulators
d.
ions
Hint
3.
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.
4.1 N/C
b.
0.24 N/C
c.
2.4 N/C
d.
0.41 N/C
Hint
4.
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 at the bottom?
a.
-3.7×10
4
J
b.
-5.5×10
4
J
c.
3.7×10
4
J
d.
1.8×10
4
J
Hint
5.
If a positively-charged glass rod is suspended so that it turns easily, and another positively-charged glass rod is brought close to it, the two rods will __________.
a.
fuse
b.
not react
c.
attract each other
d.
repel each other
Hint
6.
The multiplier for SI units with the prefix
mega
is __________.
a.
1000
b.
1/1,000,000
c.
1,000,000
d.
1/1000
Hint
7.
Three particles are placed in a line. The left particle has a charge of -47
m
C, the middle, +59
m
C, and the right, -91
m
C. The middle particle is 55 cm from each of the others. What is the net force on the middle particle?
a.
77 N, left
b.
77 N, right
c.
83 N, right
d.
160 N, right
Hint
8.
A 75.0 W lightbulb is 25.0% efficient. How many joules of thermal energy does the lightbulb produce each minute?
a.
1130 J
b.
4500 J
c.
3380 J
d.
563 J
Hint
9.
In Figure 1-10, if a fourth student measured the spring's length to be 14.2 ± 0.2 cm, would this agree with any of the other students' measurements?
a.
No.
b.
Yes, it agrees with students 1 and 3.
c.
Yes, it agrees with all three students.
d.
Yes, it agrees with only student 1.
Hint
10.
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.
9.4×10
3
N/C
b.
1.1×10
-4
N/C
c.
9.4×10
2
N/C
d.
1.1×10
-3
N/C
Hint
11.
A bike rider approaches a hill at a speed of 3.5 m/s. The mass of the bike and rider together is 77 kg. The rider coasts up the hill. Assuming that there is no friction, at what height will the bike come to rest?
a.
1.6 m
b.
4.1 m
c.
3.7 m
d.
0.62 m
Hint
12.
A kilowatt-hour is equivalent to:
a.
1.0×10
3
J
b.
1.0×10
3
J/s
c.
3.6×10
6
J
d.
3.6×10
6
J/s
Hint
13.
If the resistance of the lightbulb in Figure 22-3 were changed to 6 Ω, what would tha ammeter read?
a.
4 A
b.
2 A
c.
8 A
d.
6 A
Hint
14.
If you increase the distance between two charges, what happens to the force?
a.
It decreases.
b.
It stays the same.
c.
It vanishes.
d.
It increases.
Hint
15.
Express the quantity 0.00000095 kg in scientific notation.
a.
9.5/1,000,000 kg
b.
9.5×10
-7
kg
c.
95/1,000,000,000 kg
d.
9.5×10
7
kg
Hint
16.
An electric field is about 150 N/C downward. What is the direction of the force on a positively-charged particle?
a.
downward
b.
stationary
c.
upward
d.
changes rapidly
Hint
17.
If the the current in the circuit of Figure 22-5 is 1.5 A, what is the total resistance of the circuit?
a.
4 Ω
b.
16 Ω
c.
8 Ω
d.
18 Ω
Hint
18.
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, what would be the magnitude of the difference in the electric potential energy of the system between the initial and final positions?
a.
4.4 J
b.
3.3 J
c.
2.2 J
d.
1.1 J
Hint
19.
The apparent shift in the position of an object when it is viewed from different angles is caused by __________.
a.
faulty instruments
b.
imprecise measurement
c.
parallax
d.
inaccuracy
Hint
20.
You lift a 2.73-kg textbook from the floor to a shelf 1.75 m above the floor. What is the book's gravitational potential energy relative to the floor?
a.
14.3 J
b.
46.8 J
c.
93.1 J
d.
-46.8 J
Hint
