|
Electricity
Review Questions
Complete the statements in Questions 1,2, 3, and 4 with the
correct terms from the following list.
A. negatively
charged
B. positively charged
C. insulators
D.
conductors
1. Substances that prevent an electric charge
from escaping are said to be
2. Substances that have an excess of electrons are said to
be 3.
Substances that have a deficiency of electrons are said to
be
4. Substances in which electrons can move readily are
said to be
5. Whenever two different substances are rubbed together
they
A. become somewhat electrified.
B. become electrical conductors.
C. become magnetized.
D. repel each other.
6. When combed on a cold,
dry day, your hair tends to stand on end because
A. hair
always sticks to plastic.
B. hair is a good conductor of
electricity.
C. each separate hair has a similar charge
of electricity.
D. different hairs have opposite charges
of electricity.
7. When an ebonite rod is rubbed
with fur
A. the rod becon1es positively charged.
B. a
number of protons leave the rod.
C. the fur acquires an
equal but opposite charge to that acquired by the rod.
D. both the rod and the fur acquire a negative charge.
8. A glass rod rubbed with silk
A. becomes negatively
charged.
B. remains electrically neutral.
C.
attracts all other electrically charged bodies.
D.
becomes positively charged.
9. Which of the
following particles is electrically negative?
A. a
neutron
C. a proton
B. an electron
D. a nucleus
10. The neutral particles contained in a nucleus of an atom
are called
A. protons
B. neutrons
C.
electrons
D. photons '
11. In a neutral atom the
number of electrons is equal to A. the number of protons.
B. the number of neutrons.
C. the sum of protons and
neutrons. '
D. the difference between the number of
neutrons and the number of protons.
12. Substances
that can easily be electrified by friction are all
A.
metals B. conductors
C. insulators D. made of glass
13. When a body attracts the positively charged pith ball of
an electroscope we may infer that the body is ..
A.
positively charged
B. negatively charged
C. either negatively charged or
electrically neutral
D. electrically neutral
14. Which of the following
is classified as a good insulator?
A. graphite
B. copper wire C. a water
solution of an acid D. hard
rubber
15. When the two metal spheres L and M (see diagram) are
separated while
the negatively charged rod is still
near the sphere L
A. both spheres will remain
:uncharged.
B. both spheres will be positively
charged.
C. sphere L will be negatively charged and
sphere M will be positively charged.
D. sphere L
will be positively charged and sphere M will be
negatively charged. |  |
16. The operation of a Van Der Graff generator presents
little danger to the operator in spite of the high
voltage produced (30,000 volts or more) because
A.
the air acts as an insulator.
B. the human body is a
poor conductor of electricity.
C. the machine is
grounded.
D. a small quantity of electricity is
involved.
17. Which of the following statements
is incorrect?
A. 1 milliampere= 1/1000 ampere
B.
1 kilovolt = 1000 volts
C. 1 microvolt = 1/1000 volt
D. 1 megohm = 1,000,000 ohms
18. Which two of the
following statements are correct?
I. When cells are
connected in series the total potential difference is
equal to the sum of the voltages of the individual
cells.
II. As a rule, cells are arranged in parallel
when a large current must be sent through a large
external resistance.
III. When 100 1.5-volt dry
cells are connected in parallel, the potential
difference of the combination is equal to 150 volts.
IV. The larger the cell, the greater is the amount of
energy that can be delivered.
A. I and II
B. II and III
C. I and IV
D. II and IV
19. A coulomb is equal to 6.2 X
1018 electrons. We may conclude that the
charge on a single electron is approximately
A. 6.02
X 1023 coulombs
B. 1.6 X10-19 coulombs
C. 6.24 X 1018
coulombs
D. 96,500 coulombs
The electric current flowing
through a wire is similar to a flow of water in a pipe.
Using this analogy between hydraulics and electricity,
find in the following list of electrical terms the one
that corresponds to the concept expressed in each of
Questions 20, 21, 22, and 23. (Indicate your answer with
the letter A, B, C, or D.)
A. volts
B. coulombs
C. ohms
D. amperes
20. The quantity of water flowing
through a pipe may be measured in liters
21. The
quantity of water passing through a given point per
unit-time may be measured in liters per second. '
22. When water is forced through a pipe, the stream that
flows is reduced by the frictional resistance of the
pipe.
23. The pressure driving a quantity of water
through a pipe
24. Which of the following
formulas does not represent Ohm I s Law correctly?
A. 1 ampere = 1 volt / 1 ohm
B. V = I x R
C. I = R / V D. resistance =
potential difference/current
25. In most metals
an increase in temperature causes
A. a decrease in
resistance.
B. an increase in resistance.
C. no
change in resistance.
D. first a decrease and then a
gradual increase in resistance.
26. Wire m
has a diameter twice as large as that of wire n
of the same length and material. Wire m has a
resistance equal to
A. four times the resistance of
wire n
B. twice the resistance of wire n
C. half the
resistance of wire n
D. one-fourth the resistance of wire n
27. Which
of the following metals is the poorer conductor of
electricity? (The resistivity of each metal is given in
ohm-centimeters at 200C.)
A. mercury:
95.8 X 10-6
B. tungsten: 5.51 X 10-6
C. platinum: 10.0
X 10-6
D. silver: 1.63 X 10-6
28. The
combined (total) resistance of three resistors connected
in parallel is
A. equal to the sum of the three
resistances.
B. equal to one-third of the resistance
of anyone of them.
C. less than the resistance of
anyone of them.
D. greater than the resistance of
anyone of them. ~
29. When a 10-ohm resistor and
a 20-ohm resistor are connected in parallel, the 10-ohm
resistor carries
A. twice as much current as the
20-ohm resistor.
B. the same current as the 20-ohm resistor. -
C.
half as much current as the 20-ohm resistor.
D. none of these.
30. When the resistance of an
electrical device is measured by the voltmeter-ammeter
method the voltmeter is connected
A. in series with
the device
B. in parallel with the device
C.
across' the source of current
D. in series with the
source of current
31. A voltmeter connected to
an electric bell reads 3 volts, and an ammeter in series
with it reads 0.75 ampere. The resistance of the bell is
A. 4 ohms
B. 0.75 ohm
C. 2.25 ohms
D. 0.25 ohm
32. Which two of the following
statements are correct?
I. The current is the same
in all parts of a series circuit.
II. The voltage in
a series circuit is the same throughout the circuit.
III. The resistance of several resistors in a parallel
circuit is the sum of the separate resistances. IV. The
voltage across each of the resistors in a parallel
circuit is the same for all.
A. I and.II
B. I and III
C. I and IV
D. II and IV
33. What current flows through a
20-ohm electric toaster connected to a 120-volt line?
A. 0.166 ampere B. 100 amperes
C. 6 amperes
D. 2400 amperes
34. The resistance of a resistor
is 10 ohms and it carries a current of 5 milliamperes.
What
is the potential difference between the ends of
the resistor?
A. 0.05 volt
B. 2 volts
C. 0.5 volt
D. 50 volts
35. What is the resistance of a lamp
operating on a 120-volt line when it draws a current of
0.5 ampere?
A. 60 ohms
B. 180 ohms C.
120 ohms
D. 240 ohms
36. A 6-volt battery that has an
internal resistance of 1.5 ohms is connected to a
4.5-ohm electric bell. What current passes through the
bell?
A. 1.33. amperes
B. 36 amperes
C. 1 ampere
D. 2 amperes
37. Five lamps, all alike, have a
combined resistance of 20 ohms when connected in
parallel. What is the resistance of a single lamp?
A. 0.25 ohm
B. 4 ohms
C. 20 ohms D.
100 ohms
38. A current of 2 A is flowing through
3 resistors connected is series in a 120 V line.
Two resistors have resistances of 20 and 30 ohms
respectively. What is the resistance of the third
resistor in ohms?
A. 2.4
B. 10
C. 1.2
D. 60
|
...