Top Electrostatics Objective Questions Part – 2
1.The number of Faraday tubes of flux passing through a surface in an electric field is called
electric flux
electric flux density
magnetic flux density
electric charge density
ANSWER : : electric flux
2.A capacitance of 100 fiF is connected in series with a resistance of 8000 �2. The time constant of the circuit is
0.2 s
0.4 s
0.6 s
0.8 s
ANSWER : s: d
3.is that property of a capacitor which delays any change of voltage across it.
Inductance
Capacitance
Potential gradient
None of the above
ANSWER : : Capacitance
4.at a point may be defined as equal to the lines of force passing normally through a unit cross section at that point.
Electric intensity
Magnetic flux density
Electric flux
None of the above
ANSWER : : Electric intensity
5.Electric displacement is a______quantity.
scalar
vector
both of the above
none of the above
ANSWER : : vector
6.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,
37
42
63
73
ANSWER : : 37
7.Dielectric strength ______ with increasing thickness
increases
decreases
remains unaltered
none of the above
ANSWER : : decreases
8.The relative permittivity has the following units
F/m
m/F
Wb/m
no units
ANSWER : : Wb/m
9.What will happen to an insulating medium if voltage more than the breakdown voltage is applied on it ?
It will become magnetic
It will melt
It will get punctured or cracked
Its molecular structure will get changed
ANSWER : : It will get punctured or cracked
10.In a cable capacitor, voltage gradient ismaximum at the surface of the
earth
conduction
sheath
insulator
ANSWER : : conduction
11.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.
37, initial
63.2, initial
63.2, final
37, final
ANSWER : : 63.2, final
12.The value of E within the field due to a point charge can be found with the help of
Faraday’s laws
Kirchhoff s laws
Coulomb’s laws
none of the above
ANSWER : : Coulomb’s laws
13.A capacitor consists of two
ceramic plates and one mica disc
insulators separated by a dielectric
silver-coated insulators
conductors separated by an insulator
ANSWER : : conductors separated by an insulator
14.A unit tube of flux is known as tube
Newton
Faraday
Michale
None of the above
ANSWER : : Faraday
15.at a point is equal to the negative potential gradient at that point.
Electric intensity
Electric flux
Magnetic flux
Magnetic flux density
ANSWER : : Electric intensity
16.Electric intensity at any point in an electric field is equal to the at that point.
electric flux
magnetic flux density
potential gradient
none of the above
ANSWER : : potential gradient
17.The total deficiency or excess of electrons in a body is known as
current
voltage
potential gradient
charge
ANSWER : : charge
18.Which medium has the least dielectric strength ?
Paraffin wax
Quartz
Glass
Air
ANSWER : : Air
19.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
0.56 x 1015 m/s2
1.5 x 1015 m/s2
1.6 x 1015 m/s2
1.76 x 1015 m/s2
ANSWER : : 1.76 x 1015 m/s2
20.1 volt/metre is same as
1 metre/coulomb
1 newton metre
1 newton/metre
1 joule/coulomb
ANSWER : : 1 newton/metre
21.The property of a capacitor to store electricity is called its
capacitance
charge
energy
none of the above
ANSWER : : capacitance
22.The unit of dielectric strength is given by
V/m
V2/m
m/V
m/V2
ANSWER : : V/m
23.Dielectric strength of a material depends on
moisture content
temperature
thickness
all of the above
ANSWER : 3 none of the above
24.Permittivity is expressed in
Farad/sq-m
Farad/metre
Weber/metre
Weber/sq-m
ANSWER : : Farad/metre
25.The phenomenon of an uncharged body getting charged merely by the nearness of a charged body is known as
pholoelectric effect
chemical effect
magnetic effect
induction
ANSWER : : induction
26.The minimum value of potential gradient in a cable occurs in
insulation
conductor
outer sheath
uniformly all over
ANSWER : : insulation
27.The bridge used for the measurement of the value of the capacitance is
Wien’s bridge
Wheatstone bridge
Schering bridge
Hay’s bridge
ANSWER : : Schering bridge
28.Which of the following statements is correct ?
Mica capacitors are available in capacitance values of 5 to 20 \iF
Air capapitors have a black band to indicate the outside foil
Electrolytic capacitors must be connected in correct polarity
Ceramic capacitors must be con�nected in correct polarity
ANSWER : : Electrolytic capacitors must be connected in correct polarity
29.Which of the following capacitors preferred for high frequency circuits ?
Air capacitor
Electrolytic capacitor
Mica capacitor
none of the above
ANSWER : s: c
30.A region around a stationary electric charge has
an electric field
a magnetic field
both (a) and (b)
none of the above
ANSWER : : an electric field
31.If a third equal and similar charge is placed between two equal and similar charges, then this third charge will
move out of the field of influence of the two charges
remain in stable equilibrium
not be in equilibrium
be in unstable equilibrium
ANSWER : : remain in stable equilibrium
32.Which is the most superior dielectric out of the following ?
Air
Glass
Bakelite
Paper
ANSWER : : Bakelite
33.An electrolytic capacitor is generally made to provide
low capacitance
fixed capacitance
variable capacitance
large value of capacitance
ANSWER : : large value of capacitance
34.Paper condenser is
always polarised
usually of fixed value
electrolytic condenser
a variable condenser
ANSWER : : usually of fixed value
35.The presence of an uncharged conductor near a charged one increases the
charge of the charged conductor
capacity of the charged conductor
potential of the charged conductor
all of the above
ANSWER : : capacity of the charged conductor
36.Dielectric strength of a medium is usually expressed in
J/mm
C/m2
kV/mm
N/mm
ANSWER : : kV/mm
37.Mica capacitors are characterised by all of thte following except
stable operation
accurate value
low leakage reactance
low losses
ANSWER : : low leakage reactance
38.An uncharged conductor is placed near a charged conductor, then
the uncharged conductor gets charged by conduction
the uncharged conductor gets charged by induction and then attracted towards the charging body
the uncharged conductor is attracted first and then charged by induction
it remains as such
ANSWER : : the uncharged conductor gets charged by induction and then attracted towards the charging body
39.If an ohmmeter reading immediately goes practically to zero and stays there, capacitor is
charged
short-circuited
lossy
satisfactory
ANSWER : : short-circuited
40.A positive and a negative charge are initially 50 mm apart. When they are moved close together so that they are now only 10 mm apart, the force between them will be
5 times smaller than before
5 times greater than before
10 times greater than before
25 times larger than before
ANSWER : : 25 times larger than before
41.For a good 0.05 uF capacitor ohmmeter reading should
show low resistance momentarily and back off to a very high resis�tance
show high resistance momentarily and then a very low resistance
go quickly to 50 ohm approximately and remain there
not move at all
ANSWER : : show low resistance momentarily and back off to a very high resis�tance
42.In order to remove static electricity from machinery
construct insulated cabins
insulate the machinery
ground the framework
humidify the surroundings
ANSWER : : ground the framework
43.Out of the following capacitors of identical rating which one will have the smallest dimensions ?
Aluminium foil capacitor
Mica capacitor
Ceramic capacitor
Paper capacitor
ANSWER : : Ceramic capacitor
44.Acharge which when placed in vacuum from an equal and similar charge repels with a force of 9 x 10 N, is known as
milli-coulomb
micro-coulomb
pico-coulomb
coulomb
ANSWER : : micro-coulomb
45.When a dielectric is placed in an electric field the field strength
decreases
increases
reduces to zero
remain unchanged
ANSWER : : decreases
46.The capacitance C is charged through a resistance R. The time constant of the charging circuit is given by
CIR
1/RC
RC
RIC
ANSWER : : RC
47.Dielectric strength of medium
increases with rise in temperature
increases with moisture content
is same for all insulating materials
none of the above
ANSWER : : none of the above
48.The capacitance between two plates increases with
shorter plate area and higher ap�plied voltage
shorter plate area and shorter dis�tance between them
larger plate area, longer distance between plates and higher,applied voltage
larger plate area and shorter distance between plates
ANSWER : : larger plate area and shorter distance between plates
49.The ohmmeter reading for a short circuited capacitor is
infinity
few kilo ohms
few megaahms
zero
ANSWER : : zero
50.A potential of 400 V is applied to a capacitor, the plates of which are 4 mm apart. The strength of electric field is
100 kV/m
10 kV/m
5 kV/m
2 kV/m
ANSWER : : 100 kV/m
51.Which of the following capacitor is preferred in case of single phase motor ?
Mica capacitor
Paper capacitor
Electrolytic capacitor
Ceramic capacitor
ANSWER : : Electrolytic capacitor
52.A condenser suitable for D.C. only is
metallic plate variable gang condenser
metallic paper capacitor
oil impregrated paper condenser
poled aluminium electrolytic condenser
ANSWER : : poled aluminium electrolytic condenser
53.A capacitance is a circuit component that opposes the change in circuit
current
voltage
impedance
none of the above
ANSWER : : current
54.In a capacitor, the electric charge is stored in
metal plates
dielectric
dielectric as well as metal plates
none of the above
ANSWER : : dielectric