Note: Correct answers are marked in
green
NOTE: The correct options
are thickened in green colour. One of the major challenges you will
encountered taking your test in PHY126 is dealing with division or
multiplication of very large numbers. For example divide (9 � 109 1.6 � 10-34) say by 13 and so on. You need
to have good knowledge of indices to handle calculation in this
course.
1. Three
capacitors of capacitance, 2uF, 4uF and 8uF are
connected in parallel and a p.d of 6V is maintained across each capacitor,
the total energy stored is
A. 6.90 x 10-6J
B. 9.60 x 1 06J
C. 2.52 x 10-4
J
D. 2.52 x 10-6J
2.
Determine the force between two free electrons spaced
10-10m apart
A. 23 � 10-19N
B. 3
� 10-9N
C. 32N
D. 0.234N
3.
Which of this is not true about protons and
electrons?
A. Electrons has
equal but opposite charges as protons
B. Mass of protons is
equal to mass of electron
C. Protons repels one
another
D. Electrons repel
one another
4.
If a fully charged parallel-plate capacitor remains connected to
a battery while you slide a dielectric between the plates. How does this
affect the capacitance C and store charge Q?
A. Both C and Q
remains the same
B. C increases
and Q increases
C. C increase and Q
decreases
5.
If the potential difference across a capacitor is doubled, by
what factor does the stored energy change?
A. 2
B. 4
C. 5
D. 3
6.
A capacitor is charged with 9.6uC and a 1200V potential
difference between its terminals. Compute the capacitance and the energy
stored in it
A. 20uf and
0.534uJ
B. 34uf
and 574J
C. 80uf and
0.57uJ
D. 12uf and
234J
7.
How many electrons are responsible for 1C of
charges?
A. 62000
B.
2000
C. 62421
D. 6.2 � 10-18
8.
Two equally charged bodies are separated by a distance of 1m in
air. Evaluate the magnitude of the charge on each body if the force
between them is 360uN
A. 900C
B.
0.2uC
C.
50uC
D.
15uC
9.
A long cylindrical wire carries a charge 10-4. The
magnitude of the electric field 2.0cm from the wire
is
A. 9.0 � 107N/m
B. 4.5
� 109J.C
C. 9.0 � 109N/C
D. 4.5 � 109N/C
E. 9.0
� 109N/C
10.
Two charged bodies separated by a distance d, repel each other
with a force F. This force will change to 9F when the two bodies are
separated by a distance of _____
A. 3d
B.
9d
C. d/81
D. d/9
E. d/3
11.
Two point charges, one +2 � 10-9C, the other of -5 � 10-9C, are separated 2cm in air. What
is the magnitude of the force on the first charge?
A. 2.25 � 10-4N
B. 2.25
� 104N
C. 4.25 � 10-4N
D. 4.25 � 104N
E. 42.5
� 10-4N
12.
A potential difference of 120V generated a 100C of
electric charge through an electric heater each second. The work done by
the voltage source in 1s is______
A. 1.2 � 103J
B. 1.2
� 104J
C. 1.2 � 103eV
D. 2.4 � 103J
E. 1.2
� 10-3J
13.
Which of the following units could be properly used to
specify a voltage of 1V?
A. 1N/C
B.
1J
C. 1J/C
D. 1eV
E.
1C/F
14.
A �perfect� insulator would have
_______restivity
A.
Moderate
B.
Small
C.
Infinite
D. Zero
E.
Large
15.
The voltage across the terminals of a cell or other source of
electrical energy when no current is flowing is
A.
Electricity
B. Potential
Energy
C. Potential
Difference
D. Electroscopic
Forces
E. Electromotive
Forces
16.
Two equal but opposite charges each 1units were placed 300cm
apart. Predict the force of attraction between the two
charges?
A.
109N
B. 1.1
� 103N
C. 1.1 � 10-3N
D. 1 � 106N
E. 1
� 10-6N
17.
A spherical plate capacitor has concentric spherical
plates of radii 4cm and 2.5cm. What is the capacitance of the
capacitor?
A.
73.5uF
B.
8.00uF
C.
10.20uF
D.
15.00uF
E.
7.35uF
18.
Determine the electric field intensity created by a charge
of 10C attracted by a force 3N
A. 30 unit
B. 0.3
unit
C. 0.03
units
D. 300
units
19.
All the following are uses of capacitors
EXCEPT
A. Measurement of
Charge
B. Enable radio to
tuned to another station
C. Form vital part of
the ignition system
D. Energy
conversion
E. Store
charges
20.
The charge on an electron is 1.6 � 10‑19C. How many electrons does 1C
contains?
A. 6.25 � 1019
B. 1.60 � 1018
C. 6.25 � 1018
D. 6.25 � 10-19
E. 6.25
� 10-18
21.
Which of the following is the initial action of a dielectric
between the plates of a capacitor?
A.
Electrostatics
B. Introduction
of surface charge
C.
Polarization
D. Induced
field
E.
Conduction
22.
The capacitance of the capacitor depends only on one of the
following
A. Area of the
plate
B. Charge on
the plate
C. Geometry of the
plate
D. Potential
different of the plate
E.
Total
23.
An A/c current in 1 ohms resistor produces heat at the rate of
360W. Determine the effective value of the current and the
voltage
A. 60A, 6V
B. 6A,
60V
C. 30A,
36V
D. 6A, 6V
24.
A 7 ohms resistor is in parallel with 3ohms resistors. This
parallel combination is in series with a 5.4ohms resistor. If 30V battery
is used. What is the equivalent resistance of the entire circuit? What is
the current?
A. 5.7ohms,
4A
B. 4ohms,
7.5A
C. 7.5ohms,
4A
D. 4.5ohms,
4A
25.
A spherical plate capacitor has concentric spherical plates of
radii 4cm and 2.5cm. What is the capacitance of the
capacitor?
A. 73.5uf
B.
8.00uf
C. 10.20uf
D. 15.00uf
E.
7.35uf
26.
Which of the following is the initial action of a dielectric
between the plates of a capacitor?
A.
Electrostatics
B. Induction of the
surface charges
C.
Polarization
D. Induced
field
E.
Conduction
27.
Two equal but opposite charges are separated by a distance
of r. Which of the following will gives the expression for the force of
attraction between the charges (let K be constant of
proportionality)
A.
Kqr2
B.
Kqr-2
C.
Kq2r-2
D.
Kq2r
28.
If a voltage (V) flows through a capacitor of capacitance (C)
the work done by the voltage is express as
A.
CV2
B. �
CV2
C. CV
D. �
CV-2
29.
When a voltage (V) is apply to a capacitor the capacitor
become charged. Let the charged be donated by q. The energy stored in the
capacitor in terms of V and q can be expressed as
A. � qV
B. �
q-1V
C. �
q-1V2
D. �
qv2
30.
For the capacitors C1 C2
C3. The effective capacitance of the capacitors connected in
parallel is
A. C1 +
C2 + C3
B.
(C1+C2 +
C1C2C3)(C1C2C3)-1
C.
(C1+C2 +
C1C2C3)(C1C2C3)-1
D.
(C1+C2 +
C1C2C3)(C1C2C3)-1
31.
If the above capacitors were connected in series what will be
the equivalent capacitance of the capacitors?
A. C1 +
C2 + C3
B.
(C1+C2 +
C1C2C3)(C1C2C3)-1
C.
(C1+C2 +
C1C2C3)(C1C2C3)-1
D.
(C1+C2 +
C1C2C3)(C1C2C3)-1
32.
If the distance between two charges is double, the force of
attraction between the charges will
A. Double
B. Reduced by
half
C. Reduced by
quarter
D. Increased by
quarter
33.
If the output voltage of a transformer is greater than the
input voltage the transformer is known as
A. Step-down
B.
Step-up
C.
Step-down-up
D. Small transformer
34.
The type of transformer in a transistor radio is an
example of
A. Step-up
B.
Step-down
C.
Normal-transformer
D. DC
transformer
35.
What is the electric field intensity by a force of 45N
attracting a charge of 10C
A. 4.5
B.
450
C. 0.45
D. 0.045
36.
Determine the electric field intensity created by a charge of
100C attracted by a force 30N
A. 30 unit
B. 0.3
unit
C. 0.03
units
D. 300
units
37.
The charge on an electron is 1.6 � 10‑19C. How many electrons does 1C
contains?
A. 6.25 � 1019
B. 1.60 � 1018
C. 6.25 � 1018
D. 6.25 � 10-19
E. 6.25
� 10-18
38.
Three capacitors of capacitance, 2uF, 4uF and
8uF are connected in parallel and a p.d of 6V is maintained across
each capacitor, the total energy stored is
A. 6.90 x 10-6J
B. 9.60 x 1 06J
C. 2.52 x 10-4
J
D. 2.52 x 10-6J
39.
If a fully charged parallel-plate capacitor remains connected to
a battery while you slide a dielectric between the plates. How does this
affect the capacitance C and store charge Q?
A. Both C and Q
remains the same
B. C increases
and Q increases
C. increase and Q
decreases
40.
How many electrons are responsible for 1C of
charges?
A. 62000
B.
2000
C. 62421
D. 6.2 � 10-18
