Chapter: Electrostatics
1.

The force between two charges is 120 N. If the distance between the charges is doubled, the force will be

A. 60 N
B. 30 N
C. 40 N
D. 15 N
Answer» B. 30 N
2.

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

A. 400 N/C
B. 600 N/C
C. 800 N/C
D. 1200 N/C
Answer» C. 800 N/C
3.

The lines of force due to charged particles are

A. always straight
B. always curved
C. sometimes curved
D. none of the above
Answer» B. always curved
4.

The electric field at a point situated at a distance d from straight charged conductor is

A. proportional to d
B. inversely proportional to d
C. inversely proportional to d
D. none of the above
Answer» B. inversely proportional to d
5.

The direction of electric field due +0 positive charge is .

A. away from the charge
B. towards the charge
C. both (a) and (6)
D. none of the above
Answer» A. away from the charge
6.

A field line and an equipotential surface are

A. always parallel
B. always at 90°
C. inclined at any angle 0
D. none of the above
Answer» B. always at 90°
7.

The ability of charged bodies to exert force on 6ne another is attributed to the existence of

A. electrons
B. protons
C. neutrons
D. electric field
Answer» D. electric field
8.

If the sheet of a bakelite is inserted between the plates of an air capacitor, the capacitance will

A. decrease
B. increase
C. remains unchanged
D. become zero
Answer» B. increase
9.

A capacitor stores 0.24 coulombs at 10 volts. Its capacitance is

A. 0.024 F
B. 0.12 F
C. 0.6 F
D. 0.8 F
Answer» A. 0.024 F
10.

For making a capacitor, it is better to select a dielectric having

A. low permittivity
B. high permittivity
C. permittivity same as that of air
D. permittivity slightly more than that of air
Answer» B. high permittivity
11.

The units of capacitance are

A. volts/coulomb
B. coulombs/volt
C. ohms
D. henry/Wb
Answer» B. coulombs/volt
12.

If three 15 uF capacitors are connected in series, the net capacitance is

A. 5 uF
B. 30 uF
C. 45 uF
D. 50 uF
Answer» A. 5 uF
13.

If three 10 uF capacitors are connected in parallel, the net cararitance is

A. 20 uF
B. 30 uE
C. 40 uF
D. 50 uF
Answer» B. 30 uE
14.

A dielectric material must be

A. resistor
B. insulator
C. good conductor
D. semi conductor
Answer» B. insulator
15.

An electrolytic capacitor can be used for

A. D.C. only
B. AC. only
C. both D.C. as well as A.C.
D. none
Answer» A. D.C. only
16.

The capacitance of a capacitor is not affected by

A. distance between plates
B. area of plates
C. thickness of plates
D. all of the above
Answer» C. thickness of plates
17.

Which of the following is not a vector ?

A. Linear momentum
B. Angular momentum
C. Electric field
D. Electric potential
Answer» B. Angular momentum
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

A. Voltage across the plates increases
B. voltage across the plates decreases
C. charge on the capacitor decreases
D. charge on the capacitor increases
Answer» B. voltage across the plates decreases
19.

If A.C. voltage is applied to capacitive circuit, the alternating current can flow in the circuit because

A. varying voltage produces the charg¬ing and dicharging currents
B. of high peak value
C. charging current can flow
D. discharge current can flow
Answer» A. varying voltage produces the charg¬ing and dicharging currents
20.

Voltage applied across a ceramic dielectric produces an electrolytic field 100 times greater than air. What will be the value of dielectric constant ?

A. 50
B. 100
C. 150
D. 200
Answer» B. 100
21.

Which of the following statements is correct ?

A. Air capacitors have a blackband to indicate the outside foil
B. Electrolytic capacitor must be con¬nected in the correct polarity
C. Ceramic capacitors must be con¬nected in the correct polarity
D. Mica capacitors are available in capacitance value of 1 to 10 pF
Answer» B. Electrolytic capacitor must be con¬nected in the correct polarity
22.

The dissipation factor of a good dielectric is of the order of

A. 0.0002
B. 0.002
C. 0.02
D. 0.2
Answer» A. 0.0002
23.

"The total electric flux through any closed surface surrounding charges is equal to the amount oflcharge enclosed". The above statement is associated with

A. Coulomb's square law
B. Gauss's law
C. Maxwell's first law
D. Maxwell's second law
Answer» B. Gauss's law
24.

Three capacitors each of the capacity C are given. The resultant capacity 2/3 C can be obtained by using them

A. all in series
B. all in parallel
C. two in parallel and third in series with this combination
D. two in series and third in parallel across this combination
Answer» C. two in parallel and third in series with this combination
25.

For which of the following parameter variation, the capacitance of the capacitor remains unaffected ?

A. Distance between plates
B. Area of the plates
C. Nature of dielectric
D. Thickness of the plates
Answer» D. Thickness of the plates
26.

Which of the following statement is true ?

A. The current in the discharging capacitor grows linearly
B. The current in the dicharging capacitor grows exponentially
C. The current in the discharging capacitor decays exponentially
D. The current in the discharging capacitor decreases constantly
Answer» B. The current in the dicharging capacitor grows exponentially
27.

Which of the following expression is correct for electric field strength ?

A. E = D/E
B. E = D2/t
C. E = jtD
D. E= nD2
Answer» A. E = D/E
28.

In a capacitor the electric charge is stored in

A. metal plates
B. dielectric
C. both (a) and (6)
D. none of the above
Answer» B. dielectric
29.

Which of the following materials has the highest value of dielectric constant?

A. Glass
B. Vacuum
C. Ceramics
D. Oil
Answer» C. Ceramics
30.

Which of the following capacitors will have the least variation ?

A. Paper capacitor
B. Ceramic capacitor
C. Silver plated mica capacitor
D. None of the above
Answer» C. Silver plated mica capacitor
31.

Which of the following statements is incorrect ?

A. The leakage resistance of ceramic capacitors is generally high
B. The stored energy in a capacitor decreases with reduction in value of capacitance
C. The stored energy in a capacitor increases with applied voltage
D. A wire cable has distributed capacitance between the conductors
Answer» B. The stored energy in a capacitor decreases with reduction in value of capacitance
32.

Which of the following capacitors has relatively shorter shelf life ?

A. Mica capacitor
B. Electrolytic capacitor
C. Ceramic capacitor
D. Paper capacitor
Answer» B. Electrolytic capacitor
33.

The sparking between two electrical contacts can be reduced by inserting a

A. capacitor in parallel with contacts
B. capacitor in series with each contact
C. resistance in line
D. none of the above
Answer» A. capacitor in parallel with contacts
34.

In the case of a lossy capacitor, its series equivalent resistance value will be

A. small
B. very small
C. large
D. zero
Answer» C. large
35.

The power dissipated in a pure capacitor is

A. zero
B. proportional to applied voltage
C. proportional to value of capacitance
D. both (b) and (c) above
Answer» A. zero
36.

In a capacitive circuit

A. a steady value of applied voltage causes discharge
B. an increase in applied voltage makes a capacitor charge
C. decrease in applied voltage makes a capacitor charge
D. none of the above
Answer» B. an increase in applied voltage makes a capacitor charge
37.

When a dielectric slab is introduced in a parallel plate capacitor, the potential difference between plates will

A. remain uncharged
B. decrease
C. increase
D. become zero
Answer» B. decrease
38.

Capacitance increases with

A. increase in plate area and decrease in distance between the plates
B. increase in plate area and distance between the plates
C. decrease in plate area and value of applied voltage
D. reduction in plate area and distance between the plates
Answer» A. increase in plate area and decrease in distance between the plates
39.

A capacitor consists of

A. two insulators separated by a con¬ductor
B. two conductors separated by an in¬sulator
C. two insulators only
D. two conductors only
Answer» B. two conductors separated by an in¬sulator
40.

A paper capacitor is usually available in the form of

A. tubes
B. rolled foil
C. disc
D. meshed plates
Answer» B. rolled foil
41.

Air capacitors are generally available in the range

A. 10 to 400 pF
B. 1 to 20 pF
C. 100 to 900 pF
D. 20 to 100 pF
Answer» A. 10 to 400 pF
42.

The unit of capacitance is

A. henry
B. ohm
C. farad
D. farad/m
Answer» C. farad
43.

A capacitor charged to 200 V has 2000 (iC of charge. The value of capacitance will be

A. 10 F
B. 10 uF
C. 100 nF
D. 1000 uF
Answer» B. 10 uF
44.

A capacitor in a circuit became hot and ultimately exploded due to wrong con¬nections, which type of capacitor it could be ?

A. Paper capacitor
B. Ceramic capacitor
C. Electrolytic capacitor
D. Any-of the above
Answer» C. Electrolytic capacitor
45.

Energy stored in the electric field of a capacitor C when charged from a D.C source of voltage V is equal to joules

A. CV2
B. C2V
C. CV2
D. CV
Answer» A. CV2
46.

The absolute permittivity of free space is given by

A. 8.854 x 1(T9 F/m)
B. 8.854 x 1(T10 F/m)
C. 8.854 x KT11 F/m
D. 8.854 x 10"12 F/m
Answer» B. 8.854 x 1(T10 F/m)
47.

The relative permittivity of free space is given by

A. 1
B. 10
C. 100
D. 1000
Answer» A. 1
48.

Electric field intensity is a quantity

A. scalar
B. vector
C. both (a) and (6)
D. none of the above
Answer» B. vector
49.

When 4 volts e.m.f. is applied across a 1 farad capacitor, it will store energy of

A. 2 joules
B. 4 joules
C. 6 joules
D. 8 joules
Answer» D. 8 joules
50.

The capacitor preferred for high frequency circuits is

A. air capacitor
B. mica capacitor
C. electrolytic capacitor
D. none of the above
Answer» B. mica capacitor
51.

The capacity of capacitor bank used in power factor correction is expressed in terms of

A. kW
B. kVA
C. kVAR
D. volts
Answer» C. kVAR
52.

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

A. short-circuited
B. open circuited
C. alright
D. leaky
Answer» D. leaky
53.

If a 6 (iF capacitor is charged to 200 V, the charge in coulombs will be

A. 800 uC
B. 900 uC
C. 1200 uC
D. 1600 uC
Answer» C. 1200 uC
54.

Which capacitor will be physically smaller for the same ratings ?

A. Ceramic capacitor
B. Paper capacitor
C. Both will be of equal size
D. None of the above
Answer» A. Ceramic capacitor
55.

What is the value of capacitance that must be connected in parallel with 50 pF condenser to make an equivalent capacitance of 150 pF ?

A. 50 pF
B. 100 pF
C. 150 pF
D. 200 pF
Answer» B. 100 pF
56.

A mica capacitor and a ceramic capacitor both have the same physical dimensions. Which will have more value of capacitance ?

A. Ceramic capacitor
B. Mica capacitor
C. Both will have identical value of capacitance
D. It depends on applied voltage
Answer» A. Ceramic capacitor
57.

Which of the following material has least value of dielectric constant ?

A. Ceramics
B. Oil
C. Glass
D. Paper
Answer» B. Oil
58.

Which of the following capacitors will have the least value of breakdown voltage ?

A. Mica
B. Paper
C. Ceramic
D. Electrolytic
Answer» D. Electrolytic
59.

Dielectric constant for mica is nearly

A. 200
B. 100
C. 3 to 8
D. 1 to 2
Answer» C. 3 to 8
60.

The value of dielectric constant for vacuum is taken as

A. zero
B. 1
C. 4
D. 10
Answer» B. 1
61.

Which of the following capacitors is marked for polarity ?

A. Air
B. Paper
C. Mica
D. Electrolytic
Answer» D. Electrolytic
62.

Which of the following capacitors can be used for temperature compensation ?

A. Air capacitor
B. Ceramic capacitor
C. Paper capacitor
D. None of the above
Answer» B. Ceramic capacitor
63.

Which of the following statements is incorrect ?

A. The thinner the dielectric, the more the capacitance and the lower the voltage breakdown rating for a capacitor .
B. A six dot mica capacitor colour coded white, green, black, red and yellow has the capacitance value of 500 pF
C. Capacitors in series provide less capacitance but a higher voltage breakdown rating for the combina¬tion
D. A capacitor can store charge be¬cause it has a dielectric between two conductors
Answer» B. A six dot mica capacitor colour coded white, green, black, red and yellow has the capacitance value of 500 pF
64.

Paper capacitors usually have a tolerance of

A. ± 5%
B. ± 10%
C. ± 15%
D. ± 20%
Answer» B. ± 10%
65.

For closer tolerances which of the following capacitors is usually preferred ?

A. Paper capacitor
B. Mica capacitor
C. Ceramic disc capacitor
D. None of the above
Answer» B. Mica capacitor
66.

The electrostatic force between two charges of one coulomb each and placed at a distance of 0.5 m will be

A. 36 x 10fa
B. 36 x 107 N
C. 36 x 108 N
D. 36 x 109 N
Answer» D. 36 x 109 N
67.

The units of volume charge density are

A. Coulomb/metre
B. Coulomb/metre
C. Coulomb/metre
D. Coulomb/metre
Answer» C. Coulomb/metre
68.

"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

A. Gauss's law
B. Kirchhoff s law
C. Faraday's law
D. Lenz's law
Answer» A. Gauss's law
69.

Dielectric strength of mica is

A. 10 to 20 kV/mm
B. 30 to 50 kV/mm
C. 50 to 200 kV/mm
D. 300 to 500 kV/mm
Answer» C. 50 to 200 kV/mm
70.

The dielectric constant (relative permittivity) of glass is given by

A. 0.1 to 0.4
B. 0.5 to 1.0
C. 2.0 to 4.0
D. 5 to 100
Answer» D. 5 to 100
71.

capacitors are mainly used for radio frequency tuning.

A. Paper
B. Air
C. Mica
D. Electrolytic
Answer» B. Air
72.

capacitors can be used only for D.C.

A. Air
B. Paper
C. Mica
D. Electrolytic
Answer» D. Electrolytic
73.

capacitors are used in transistor circuits.

A. Ceramic
B. Paper
C. Air
D. Electrolytic
Answer» A. Ceramic
74.

capacitors are used for audio frequency and radio frequency coupling and tuning.

A. Air
B. Mica
C. Plastic film
D. Ceramic
Answer» B. Mica
75.

The inverse of capacitance is called

A. reluctance
B. conductance
C. susceptance
D. elastance
Answer» D. elastance
76.

When the dielectric is homogeneous,the potential gradient is

A. uniform
B. non-uniform
C. zero
D. any of the above
Answer» A. uniform
77.

The potential gradient across the material of low permittivity is than across the material of high permittivity.

A. smaller
B. greater
C. both (a) and (b)
D. none of the above
Answer» B. greater
78.

________field is associated with the capacitor.

A. Electric
B. Magnetic
C. Both (a) and (b)
D. None of the above
Answer» A. Electric
79.

A capacitor having capacitance of 5 uF is charged to a potential difference of 10,000 V. The energy stored in the capacitor is

A. 50 joules
B. 150 joules
C. 200 joules
D. 250 joules
Answer» D. 250 joules
80.

A single core cable used on 33000 V has conductor diameter 10 mm and the in¬ternal diameter of sheath 25 mm. The maximum electrostatic stress in the cable is

A. 62 x 105 V/m
B. 72 x 105 V/m
C. 82 x 105 V/m
D. 92 x 105 V/m
Answer» B. 72 x 105 V/m
81.

Two infinite parallel plates 10 mm apart have maintained between them a potential difference of 100 V. The acceleration of an electron placed between them is

A. 0.56 x 1015 m/s2
B. 1.5 x 1015 m/s2
C. 1.6 x 1015 m/s2
D. 1.76 x 1015 m/s2
Answer» D. 1.76 x 1015 m/s2
82.

The total deficiency or excess of electrons in a body is known as

A. current
B. voltage
C. potential gradient
D. charge
Answer» D. charge
83.

The relative permittivity has the following units

A. F/m
B. m/F
C. Wb/m
D. no units
Answer» C. Wb/m
84.

The phenomenon of an uncharged body getting charged merely by the nearness of a charged body is known as

A. pholoelectric effect
B. chemical effect
C. magnetic effect
D. induction
Answer» D. induction
85.

A unit tube of flux is known as tube

A. Newton
B. Faraday
C. Michale
D. None of the above
Answer» B. Faraday
86.

The number of Faraday tubes of flux passing through a surface in an electric field is called

A. electric flux
B. electric flux density
C. magnetic flux density
D. electric charge density
Answer» A. electric flux
87.

The value of E within the field due to a point charge can be found with the help of

A. Faraday's laws
B. Kirchhoff s laws
C. Coulomb's laws
D. none of the above
Answer» C. Coulomb's laws
88.

at a point may be defined as equal to the lines of force passing normally through a unit cross section at that point.

A. Electric intensity
B. Magnetic flux density
C. Electric flux
D. None of the above
Answer» A. Electric intensity
89.

Electric intensity at any point in an electric field is equal to the at that point.

A. electric flux
B. magnetic flux density
C. potential gradient
D. none of the above
Answer» C. potential gradient
90.

Electric displacement is a______quantity.

A. scalar
B. vector
C. both of the above
D. none of the above
Answer» B. vector
91.

at a point is equal to the negative potential gradient at that point.

A. Electric intensity
B. Electric flux
C. Magnetic flux
D. Magnetic flux density
Answer» A. Electric intensity
92.

The unit of dielectric strength is given by

A. V/m
B. V2/m
C. m/V
D. m/V2
Answer» A. V/m
93.

Dielectric strength ______ with increasing thickness

A. increases
B. decreases
C. remains unaltered
D. none of the above
Answer» B. decreases
94.

The property of a capacitor to store electricity is called its

A. capacitance
B. charge
C. energy
D. none of the above
Answer» A. capacitance
95.

is that property of a capacitor which delays any change of voltage across it.

A. Inductance
B. Capacitance
C. Potential gradient
D. None of the above
Answer» B. Capacitance
96.

A capacitance of 100 fiF is connected in series with a resistance of 8000 £2. The time constant of the circuit is

A. 0.2 s
B. 0.4 s
C. 0.6 s
D. 0.8 s
Answer» D. 0.8 s
97.

In a cable capacitor, voltage gradient ismaximum at the surface of the

A. earth
B. conduction
C. sheath
D. insulator
Answer» B. conduction
98.

The time constant of an R-C circuit is defined as the time during which capacitor charging voltage actually rises to ______ percent of its______value.

A. 37, initial
B. 63.2, initial
C. 63.2, final
D. 37, final
Answer» C. 63.2, final
99.

The time constant and R-C circuit may also be defined as the time during which the charging current falls to ______ percent of its initial maximum value,

A. 37
B. 42
C. 63
D. 73
Answer» A. 37
100.

A capacitor consists of two

A. ceramic plates and one mica disc
B. insulators separated by a dielectric
C. silver-coated insulators
D. conductors separated by an insulator
Answer» D. conductors separated by an insulator
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