100 Objective Questions On Electrostatics
1.The direction of electric field due +0 positive charge is .
away from the charge
towards the charge
both (a) and (b)
none of the above
ANSWER : : away from the charge
2.The lines of force due to charged particles are
always straight
always curved
sometimes curved
none of the above
ANSWER : : always curved
3.Three capacitors each of the capacity C are given. The resultant capacity 2/3 C can be obtained by using them
all in series
all in parallel
two in parallel and third in series with this combination
two in series and third in parallel across this combination
ANSWER : : two in parallel and third in series with this combination
4.For making a capacitor, it is better to select a dielectric having
low permittivity
high permittivity
permittivity same as that of air
permittivity slightly more than that of air
ANSWER : : high permittivity
5.Voltage applied across a ceramic dielectric produces an electrolytic field 100 times greater than air. What will be the value of dielectric constant ?
50
100
150
200
ANSWER : : 100
6.Which of the following statements is correct ?
Air capacitors have a blackband to indicate the outside foil
Electrolytic capacitor must be con�nected in the correct polarity
Ceramic capacitors must be con�nected in the correct polarity
Mica capacitors are available in capacitance value of 1 to 10 pF
ANSWER : : Electrolytic capacitor must be con�nected in the correct polarity
7.Which of the following is not a vector ?
Linear momentum
Angular momentum
Electric field
Electric potential
ANSWER : : Angular momentum
8.For which of the following parameter variation, the capacitance of the capacitor remains unaffected ?
Distance between plates
Area of the plates
Nature of dielectric
Thickness of the plates
ANSWER : : Thickness of the plates
9.If the sheet of a bakelite is inserted between the plates of an air capacitor, the capacitance will
decrease
increase
remains unchanged
become zero
ANSWER : : increase
10.Which of the following statement is true ?
The current in the discharging capacitor grows linearly
The current in the dicharging capacitor grows exponentially
The current in the discharging capacitor decays exponentially
The current in the discharging capacitor decreases constantly
ANSWER : : The current in the dicharging capacitor grows exponentially
11.The ability of charged bodies to exert force on 6ne another is attributed to the existence of
electrons
protons
neutrons
electric field
ANSWER : : electric field
12.An electrolytic capacitor can be used for
D.C. only
AC. only
both D.C. as well as A.C.
D.C. only
ANSWER : he capacitance of a capacitor is not affected by
13.A field line and an equipotential surface are
always parallel
always at 90�
inclined at any angle 0
none of the above
ANSWER : : always at 90�
14.A capacitor stores 0.24 coulombs at 10 volts. Its capacitance is
0.024 F
0.12 F
0.6 F
0.8 F
ANSWER : : 0.024 F
15.If A.C. voltage is applied to capacitive circuit, the alternating current can flow in the circuit because
varying voltage produces the charg�ing and dicharging currents
of high peak value
charging current can flow
discharge current can flow
ANSWER : : varying voltage produces the charg�ing and dicharging currents
16.A dielectric material must be
resistor
insulator
good conductor
semi conductor
ANSWER : : insulator
17.The dissipation factor of a good dielectric is of the order of
0.0002
0.002
0.02
0.2
ANSWER : : 0.0002
18.Two plates of a parallel plate capacitor after being charged from a constant voltage source are separated apart by means of insulated handles, then the
Voltage across the plates increases
voltage across the plates decreases
charge on the capacitor decreases
charge on the capacitor increases
ANSWER : : voltage across the plates decreases
19.If three 10 uF capacitors are connected in parallel, the net cararitance is
20 uF
30 uE
40 uF
50 uF
ANSWER : : 30 uE
20.If three 15 uF capacitors are connected in series, the net capacitance is
5 uF
30 uF
45 uF
50 uF
ANSWER : : 5 uF
21.”The total electric flux through any closed surface surrounding charges is equal to the amount oflcharge enclosed”. The above statement is associated with
Coulomb’s square law
Gauss’s law
Maxwell’s first law
Maxwell’s second law
ANSWER : : Gauss’s law
22.The units of capacitance are
volts/coulomb
coulombs/volt
ohms
henry/Wb
ANSWER : s: b
23.The electric field at a point situated at a distance d from straight charged conductor is
proportional to d
inversely proportional to d
inversely proportional to d
none of the above
ANSWER : : inversely proportional to d
24.The electric field intensity at a point situated 4 metres from a point charge is 200 N/C. If the distance is reduced to 2 metres, the field intensity will be
400 N/C
600 N/C
800 N/C
1200 N/C
ANSWER : : 800 N/C
25.While testing a capacitor with ohm-metre, if the capacitor shows charging, but the final resistance reading is appreciably less than normal, it can be concluded that the capacitor is
short-circuited
open circuited
alright
leaky
ANSWER : : leaky
26.When 4 volts e.m.f. is applied across a 1 farad capacitor, it will store energy of
2 joules
4 joules
6 joules
8 joules
ANSWER : : 8 joules
27.The sparking between two electrical contacts can be reduced by inserting a
capacitor in parallel with contacts
capacitor in series with each contact
resistance in line
none of the above
ANSWER : : capacitor in parallel with contacts
28.In a capacitive circuit
a steady value of applied voltage causes discharge
an increase in applied voltage makes a capacitor charge
decrease in applied voltage makes a capacitor charge
none of the above
ANSWER : : an increase in applied voltage makes a capacitor charge
29.A capacitor in a circuit became hot and ultimately exploded due to wrong con�nections, which type of capacitor it could be ?
Paper capacitor
Ceramic capacitor
Electrolytic capacitor
Any-of the above
ANSWER : : Electrolytic capacitor
30.In a capacitor the electric charge is stored in
metal plates
dielectric
both (a) and (b)
none of the above
ANSWER : s: b
31.Air capacitors are generally available in the range
10 to 400 pF
1 to 20 pF
100 to 900 pF
20 to 100 pF
ANSWER : : 10 to 400 pF
32.Which of the following statements is incorrect ?
The leakage resistance of ceramic capacitors is generally high
The stored energy in a capacitor decreases with reduction in value of capacitance
The stored energy in a capacitor increases with applied voltage
A wire cable has distributed capacitance between the conductors
ANSWER : : The stored energy in a capacitor decreases with reduction in value of capacitance
33.The capacity of capacitor bank used in power factor correction is expressed in terms of
kW
kVA
kVAR
volts
ANSWER : : kVAR
34.The capacitor preferred for high frequency circuits is
air capacitor
mica capacitor
electrolytic capacitor
none of the above
ANSWER : : mica capacitor
35.A capacitor consists of
two insulators separated by a con�ductor
two conductors separated by an in�sulator
two insulators only
two conductors only
ANSWER : : two conductors separated by an in�sulator
36.Which of the following materials has the highest value of dielectric constant?
Glass
Vacuum
Ceramics
Oil
ANSWER : : Ceramics
37.The unit of capacitance is
henry
ohm
farad
farad/m
ANSWER : : farad
38.Capacitance increases with
increase in plate area and decrease in distance between the plates
increase in plate area and distance between the plates
decrease in plate area and value of applied voltage
reduction in plate area and distance between the plates
ANSWER : s: a
39.A capacitor charged to 200 V has 2000 (iC of charge. The value of capacitance will be
10 F
10 uF
100 nF
1000 uF
ANSWER : : 10 uF
40.The absolute permittivity of free space is given by
8.854 x 1(T9 F/m)
8.854 x 1(T10 F/m)
8.854 x KT11 F/m
8.854 x 10″12 F/m
ANSWER : : 8.854 x 1(T10 F/m)
41.If a 6 (iF capacitor is charged to 200 V, the charge in coulombs will be
800 uC
900 uC
1200 uC
1600 uC
ANSWER : : 1200 uC
42.The relative permittivity of free space is given by
1
10
100
1000
ANSWER : : 1
43.Electric field intensity is a quantity
scalar
vector
both (a) and (b)
none of the above
ANSWER : : vector
44.Energy stored in the electric field of a capacitor C when charged from a D.C source of voltage V is equal to joules
CV2
C2V
CV2
CV
ANSWER : : CV2
45.The power dissipated in a pure capacitor is
zero
proportional to applied voltage
proportional to value of capacitance
both (b) and (c) above
ANSWER : : zero
46.capacitors can be used only for D.C.
Air
Paper
Mica
Electrolytic
ANSWER : : Electrolytic
47.Which of the following capacitors can be used for temperature compensation ?
Air capacitor
Ceramic capacitor
Paper capacitor
None of the above
ANSWER : : Ceramic capacitor
48.Which of the following capacitors is marked for polarity ?
Air
Paper
Mica
Electrolytic
ANSWER : : Electrolytic
49.capacitors are used in transistor circuits.
Ceramic
Paper
Air
Electrolytic
ANSWER : : Ceramic
50.Paper capacitors usually have a tolerance of
� 5%
� 10%
� 15%
� 20%
ANSWER : : � 10%
51.The dielectric constant (relative permittivity) of glass is given by
0.1 to 0.4
0.5 to 1.0
2.0 to 4.0
5 to 100
ANSWER : : 5 to 100
52.A mica capacitor and a ceramic capacitor both have the same physical dimensions. Which will have more value of capacitance ?
Ceramic capacitor
Mica capacitor
Both will have identical value of capacitance
It depends on applied voltage
ANSWER : : Ceramic capacitor
53.Which of the following material has least value of dielectric constant ?
Ceramics
Oil
Glass
Paper
ANSWER : : Oil
54.Which of the following statements is incorrect ?
The thinner the dielectric, the more the capacitance and the lower the voltage breakdown rating for a capacitor .
A six dot mica capacitor colour coded white, green, black, red and yellow has the capacitance value of 500 pF
Capacitors in series provide less capacitance but a higher voltage breakdown rating for the combina�tion
A capacitor can store charge be�cause it has a dielectric between two conductors
ANSWER : : A six dot mica capacitor colour coded white, green, black, red and yellow has the capacitance value of 500 pF
55.For closer tolerances which of the following capacitors is usually preferred ?
Paper capacitor
Mica capacitor
Ceramic disc capacitor
None of the above
ANSWER : : Mica capacitor
56.Dielectric constant for mica is nearly
200
100
3 to 8
1 to 2
ANSWER : s: c
57.Dielectric strength of mica is
10 to 20 kV/mm
30 to 50 kV/mm
50 to 200 kV/mm
300 to 500 kV/mm
ANSWER : : 50 to 200 kV/mm
58.The units of volume charge density are
Coulomb/metre
Coulomb/metre
Coulomb/metre
Coulomb/metre
ANSWER : : Coulomb/metre
59.The electrostatic force between two charges of one coulomb each and placed at a distance of 0.5 m will be
36 x 10fa
36 x 107 N
36 x 108 N
36 x 109 N
ANSWER : : 36 x 109 N
60.What is the value of capacitance that must be connected in parallel with 50 pF condenser to make an equivalent capacitance of 150 pF ?
50 pF
100 pF
150 pF
200 pF
ANSWER : : 100 pF
61.________field is associated with the capacitor.
Electric
Magnetic
Both (a) and (b)
None of the above
ANSWER : : Electric
62.capacitors are used for audio frequency and radio frequency coupling and tuning.
Air
Mica
Plastic film
Ceramic
ANSWER : : Mica
63.”The surface integral of the normal component of the electric displacement D over any closed surface equals the charge enclosed by the surface”. The above statement is associated with
Gauss’s law
Kirchhoff s law
Faraday’s law
Lenz’s law
ANSWER : : Gauss’s law
64.The potential gradient across the material of low permittivity is than across the material of high permittivity.
smaller
greater
both (a) and (b)
none of the above
ANSWER : : greater
65.The inverse of capacitance is called
reluctance
conductance
susceptance
elastance
ANSWER : : elastance
66.A capacitor having capacitance of 5 uF is charged to a potential difference of 10,000 V. The energy stored in the capacitor is
50 joules
150 joules
200 joules
250 joules
ANSWER : : 250 joules
67.The value of dielectric constant for vacuum is taken as
zero
1
4
10
ANSWER : : 1
68.Which of the following capacitors will have the least value of breakdown voltage ?
Mica
Paper
Ceramic
Electrolytic
ANSWER : : Electrolytic
69.When the dielectric is homogeneous,the potential gradient is
uniform
non-uniform
zero
any of the above
ANSWER : : uniform