12th Physics Additional Questions (Vol 1)

8/9/2019 12th Physics Additional Questions (Vol 1)

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1 BHARATHIDASANAR MATRIC HIGHER SECONDARY SCHOOL, ARAKKONAM_12th

Physics Additional Questions

BHARATHIDASANAR MATRICULATION

HIGHER SECONDARY SCHOOL,

ARAKKONAM.

12th STANDARD PHYSICS ADDITIONAL

QUESTIONS

ADDITIONAL 1 MARK QUESTIONS WITH KEY

ANSWERS

VOLUME - I

Created by

Department of PhysicsPh: 91-9380899694


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1.ELECTROSTATICS

1.When a glass slab in introduced between two charged spheres, the force

between them

a) in increases b) remains same c) is reduced

d) is increased or decreased, depending on the thickness of slab

2.Two charged spheres A and B are separated by a distance. If a third

charged sphere C is brought near to them , then the force between A and B

a) increases b) decreases c) remains same

d) either increases or decreases depending on nature of charge in C.

3.Two point charge +3µC are separated by a distance of 0.4m . Whereshould a third charge +2µC be placed from +3µC .So that it experience s

zero force.

a) 0.4m b) 0.5m c) 0.2m d) 0.1m4.Two charges 250µC and 120µC placed 15mm apart in medium repel each

other with 105 N. Then the value of dielectric constant.

a) 14 b) 16 c) 13 d) 125.Charges 1mC, 0.5mC, -1mC -0.5mC are placed at four corners of square

ABCD of sides1.414m. The electric field at the centre of the square must be

a) 95x106 NC-1 along AB b) 35x106 NC-1 along BCc) 35x106 NC-1 along AB d) 95x106 NC-1 along BC

6.Two point charges +8µC and +4µC repel each other with a force 16N.If a

charge of -6C is given to each other , what will be the force now,a) 4N(attractive) b)4N(repulsive) c) 2N(repulsive) d) 2N(attractive)

7.In an microwave oven ,heat is produced due to

a) oscillating of water molecule b)oscillating torque on water moleculesc) molecular reaction of current by thermodynamic heating

d)breaking of bonds in water molecule

8.If a proton is moved against the coulomb force of electric field

a) work is done by electric field b) energy is supplied from outside sourcec) energy of proton is decreased d) strength of electric field decreased


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9.Two point charges 8C and 2C are separated by a distance of 9 cm. The

point where the electric field becomes zero isa) 6 cm from 8C b) 3 cm from 2C c) 3 cm from 8C d) both(a)and (b)

10.Two ideal spheres of charges8C and -4C are 0.02 m apart. They are

brought in conduct and then replaced to their original position, the ratioof force between them before and after contact is

a) 4:1 b) 1:8 c) 1:4 d) 8:1

11.Two protons repel each other with a force of 22.5 N ,the distance of

separation is

a) 3.2x10-12

m b) 3.2x10-14

m c) 3.2x10-15

m d) 3.2A0

12.How a charge of 9C is divided into two parts to have a maximum force of

repulsion when separated by certain distance

a) 6C,3C b) 8C,1C c) 5C,4C d) 7C,2C13.The force between two charges in vacuum is 0.1N. What is the force if

the vacuum is replaced by a medium of permittivity 10 times vacuum,a) 1N b) 0.01N c) 10N d) 0.001 N

14.The ratio of electric field intensities at a distance “ r ” from the centre of a

small dipole along axial and equatorial line is

a) 1:2 b) 1:4 c) 4:1 d) 2:1

15.A body charged to 4.8x10-20

C by applying a potential difference of

500 mV. This isa) true because body can store charge

b) false , because potential difference applied is not enough

c) false, because charge must be integral multiple of electrond) true, because charge is directly proportional to potential difference.

16.Two point charges separated by distance d1exerts force F1 and distanced2 the force is F2 , then,

a) F1d2 = F2d12 b) F1

2 d1 = F2d2

2 c) F1

2 d2 = F2

2 d1 d) F1d1

2 = F2

2 d2

2

17.The effective capacitances of two capacitors connected in parallel is equal

to thea)product of the capacitances b) differences between the capacitors

c) the ratio between the capacitance d) sum of the capacitances

18.The force of attraction between two spheres of charge q and -q is F. If

two spheres are brought into contact and then separated to twice the

previous distance the force now,


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a) F/2 b) F/4 c) 4F d) zero

19.Work done for rotating the dipole in an electric field isa) kinetic energy b) potential energy c) total energy d)each of these

20.Which one is the application of electric potential energy of an electric

dipole in electric fielda) capacitor b) inductor c) room heater d) microwave oven

21.The negative gradient of potential gives the magnitude of the

a) electric field b) magnetic field c) magnetic flux d) electric flux

22.The quantity which is same at all points in an equipotential surface is

a) potential b) current c) charge d) mass

23.The equipotential surfaces of an isolated point charge are

a) concentric spheres b) square c) cylindrical d) triangle

24.Work done in moving a point charge between two points on an

equipotential surface isa) zero b) one c) maximum d) minimum

25.Electric field lines are … to an equipotential surfacea)normal b) parallel c) 45

0 d) zero

26.The equipotential surfaces for a uniform electric field are

a) parallel planes b) tangential planes

c) normal planes d)cleavage planes

27.The work done in moving 500µC charge between two points on

equipotential surface isa) zero b) finite ,positive c) finite , negative d) infinite negative

28.A charge Q is placed at the centre of a cube. The electric flux through all

the 6 faces of the cube is

a) Q/60 b) Q/80 c) Q/0 d) zero29.Capacitor stores

a) magnetic energy b) chemical energy

c) electrical energy d)heat energy

30.A hallow insulated conducting sphere is given by a positive charge of

10 µC. What will be the electric field at the centre of the sphere, if itsradius is 2m?

a) zero b) 5 µC m-2

c) 20C m-2

d) 32 µC m-2

31.Capacitors use the principle of

a) self induction b) mutual induction

c) electrostatic induction d) dielectric polarization


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32.The capacitance of a conductor does not depend upon

a) its geometry b) material by which plates are madec) nature of medium d) area of the plates

33.An air filled parallel plate capacitor connected to a battery and allowed to

charge. If a dielectric slab is placed between the plates of the capacitora) the charge on the capacitor remains un changes

b) the charge on the capacitors increasesc) the voltage across the plates of the capacitor increases

d) the capacitance of the capacitor decreases

34.On a conductor the surface charge density at a point is

a) directly proportional to the radius of curvature

b) inversely proportional to the radius of curvature

c) independent of radius of curvature at that point. d) zero

35.If a Gaussian surface encloses a dipole of moment 2qd, then the total fluxthrough the surface is

a) q / 0 b) 2q/0 c) q/20 d) zero36.Work done in giving a charge of 8x10

-12C on a condenser of capacity

100µF is

a) 32x10-32

J b) 32x10-20

J c) 8x10-12

J d) 4x10-32

J

37.Two charged metal spheres of radii 2 cm and 5 cm are connected by a

wire. The ratio of the surface charge densities is

a)2.5 b) 0.4 c) 12.5 d) 538.The capacitance of a parallel plate capacitor is 8 µF. If the surface area is

doubled and the distance between the plates is halved .Then what will be

the capacitance of the condenser?a) 12 µF b) 32 µF c) 4 µF d) 8 µF

39.Relative permittivity of vacuum is

a) 3 b) 1 c) 2 d) 0

40.The charge that can be stored in 50 µF capacitor connected to source of

potential difference of 20V is

a) 102C b) 10-3C c) 1C d) 103 C41.An infinite charged plane sheet produces a field of 2x10

5 NC

-1 at a

distance of 5 cm, the surface charge density isa) 3.54x10

-6Cm

-2 b) 3.54x10

-6Cm c) 0.54x10

-2Cm

d) 18.53x10

-3Cm

42.A device not working with the principle of electrostatic induction is

a) van de Graff generator b) microwave oven


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c) lightning arrestor d) (a) &(b)

43.A parallel plate capacitor connected to a 12V source is charged to 21 µCif the capacitor is filled with an oil of dielectric constant 3, then the

charge stored is

a) 7 µC b) 63µC c) 14 µC d) 57 µC44.The equivalent capacitance of two capacitors in series is 1.5µF. The

capacitance of one of them is 4µF .The value of capacitance of other isa)2.4µF b) 0.24µF c) 0.417µF d) 4.17µF

45.If the distance between two protons in uranium atom is 9x10-15

m, then the

mutual electric potential energy between them is

a) 9x10-14

J b) 1.44x10-15

J c) 2.56x10-14

J d) 1.6x10-5

J

46.Torque on a dipole in a uniform electric field is maximum when angle

between P and E is

a) 00

b) 900

c) 450

d) 1800

47.Potential energy of two equal negative point charges of magnitude 2 µC

placed 1m apart in air isa) 2J b) 0.36J c)4J d) 0.036J

48.An electric dipole placed at an angle in a non-uniform electric fieldexperiences

a) neither a force nor a torque b) torque only

c) both force and torque d) force only

49.Which of the following is not a dielectric ?a) ebonite b) mica c) oil d) gold

50.The electric field intensity at a distance r due to infinitely long straight

charged wire is directly proportional toa) r b) 1/r c) r

2 d) 1/r

2

51.An electric dipole moment P is placed in a uniform electric field of

intensity E at an angle with respect to the field . The direction of thetorque is

a) along the direction of P b) opposite to the direction of P

c) along the direction of E d) perpendicular to the plane containing P &E

52.The capacitance of a capacitor is

a) directly proportional to the charge q given to it b) inversely proportional to its potential V

c) directly proportional to q and inversely proportional to V

d) independent of both the charge q and potential V


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53.The intensity of electric field at a point is equal to

a) the force experienced by a charge q b) the work done in bringing unit positive charge from infinity to that

point

c) the positive gradient of the potential d)the negative gradient of the potential

54.The unit of the number of electric lines of force passing through a givenarea is

a) no unit b) NC-1

c) Nm2C

-1 d) N m

55.A dielectric medium is placed in an electric field E0.The field induced

inside the medium

a) acts in the direction of the electric field b) acts opposite to E0

c)acts perpendicular to E0 d) is zero

56.A non-polar dielectric is placed in an electric field (E) . Its induced dipolemoment

a) acts perpendicular to E b) acts in the direction of Ec) acts opposite to the direction of E d) is zero

57.When the charge given to a capacitor is doubled , its capacitance

a) increases twice b) decreases twice

c) increases four times d) does not change

58.Two point charges +q and –q are placed at A and B separated by small

distance. The electric field intensity at the midpoint o of ABa) zero b) acts along AB c) acts along BA d) acts to AB

59.An electric dipole of dipole moment (P) is kept parallel to an electric field

of intensity E. The work done in rotating the dipole through 900is

a) 0 b) –PE c) PE d) 2pE

60.The capacitance of a parallel plate capacitor given a charge q is C. If thecharge on the capacitor is doubled then the capacitance of the capacitor is

a) C b) 2C c) C/2 d) 2/C

61.The accumulation of charge in a charged conductor is maximum at

a) a point where the curvature is maximum b) sharp pointsc) a point where the radius is minimum d) all the above

62.Radius of conductor is r and its charge density is , thena) r b) 1/r c) 1/r 2 d) r 2

63.In microwave oven, the water molecules are excited by

a) force b) oscillating torque c) oscillating force d) a torque


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64.Which molecule do not have a permanent dipole moment?

a) N2O b) NH4 c) H2O d) O265.In electrostatic induction

a) like charges were induced at the near end b) only unlike charges were

inducedc) unlike charges induced at near end and like charge induced at far end

d) only like charges were induced66.In a parallel plate capacitor, the electric field at any point between the

plates does not depend on

a) distance between the plates b) charge on the plates

c) area of the plates d) the dielectric media between the plates.

67.In a thin , non conducting infinite plane sheet 1.6µC charge are present in

the area2mm2.Calculate the surface density

a) 8C/m2

b) 0.8C/m2 c) 32x10

3C/m

2 d) 2.25x10

-6C/m

2

68.The force between two charges in a medium of dielectric constant D andin the air is

a) 1:D b) 1:D2 c) D:1 d) D

2:1

69.The charges in the electrostatic field are analogous to which in a

gravitational field

a) distance b) forces c) masses d) points

70.Two copper spheres A and B of same size are charged to same potential.A is hollow and B is solid. Which of the two fields holds more charge?

a) solid sphere cannot hold any charge b) both have the same charge

c) hollow sphere cannot hold any charge d) both have zero charge71.The relative permittivity is one for

a) glass b) mica c) air d) earth72.The repulsive force between two like charges of 1 coulomb separated by

a distance of 1 m in vacuum is equal to

a) 9x109 N b) 10

9 N c) 9x10

-9 N d) 9N

73.When air is replaced by dielectric medium of dielectric constant K, themaximum force of attraction between two charges separated by a

distance

a) becomes K -1

times b) decrease K 2times

c) remains unchanged d) increases K times

74.Which of the following does not have a permanent electrical dipole


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moment?

a) ammonia b) water c) nitrogen d) carbon di oxide75.Normally the charge of a substance is

a) having any value b) a constant

c) an integral multiple of the charge of an electron d) is an integer76.In an equipotential surface which is same at all points

a)electric intensity b) electric force c) electric potential d) electric flux77.A bird sitting on a high power line

a) gets killed instantly b) gets a mild shock

c) is not affected practically d) gets a fatal shock

78.An electron initially at rest is accelerated through a potential difference of

1 volt. The energy acquired by electrons is

a) 1J b) 1.6x10-19

J c) 10-19

J d) 1.6x1019

J

79.In bringing an electron ,towards another electron, the electrostatic

potential energy of the systema) remains constant b) becomes zero c) increases d) decreases

80.Four dipoles of charges of magnitude +e and –e are placed inside a cube.

The total electric flux coming out of the cube will be

a) 8e/0 b) 16e/0 c) e/0 d) zero81.The direction of electric field due to an infinitely long straight positively

charged wire isa) radially inward b) along the length of the wire

c) radially outwards d) none of the above

82. The direction of electric field due to an infinitely long straight nrgativelycharged wire is

a) radially inward b) along the length of the wire

c) radially outwards d) none of the above

83.An electric dipole consists of

a) two like and equal charges b) like and unequal charges

c) unlike and equal charges d) unlike and unequal charges84.When the charging source is disconnected , the charges given to the plates

of an ideal capacitora) increases b) decreases c) becomes zero d) remains the same

85.Increasing the charge on the plates of a capacitor means

a) increasing the capacitance b) increasing the p.d. between the plates


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c) both (a) and (b) d) none of the above

86.Three capacitors 2F, 5F and 3F are in parallel across 5V supply. Thecharge on each of them respectively are

a) 12C,30C,18C b) 10C, 25C,15Cc)8C, 20C,12C d) 6C,15C,9C

87.Capcity of the conductor depends upon

a) size of the conductor b) thickness of the conductor

c) material of the conductor d) all of these88.A capacitor is a device for

a) increasing voltage in the circuit `

b) increasing the current in the circuitc) storing the charges d) giving resistance to the current

89.A dielectric will have

a) free electrons b) no electrons

c) tightly bound electrons d) one electron in the outer orbit90.A charged conductor with sharp points on its surface

a) gains charge b) neither gains nor loose charge

c) rapidly lose its charge d) gets rusted soon

91.A non-polar molecule acquires induced dipole moment

a) opposite to the direction to the electric field

b) perpendicular to the electric field c) in the direction of the electric fieldd) none of the above

92.In the absence of an external field , the net dipole moment of polar

molecules isa) positive b) infinite c) negative d) zero

93.If a dielectric slab is introduced between the plates of a capacitor , the

dielectric slab gets

a) positive charge b) polarized c) negative charge d) neutralized

94.The number of electric lines of force produced by a unit charge in

vacuum

a)1/0 b) 1012

/8.854 c) 36x109 d) all of these95.When a glass slab is introduced in between the plates of a parallel plate

air condenser, its capacitance will

a) not change b) decreases c) increases d) tends to zero


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96.The energy recovered if a capacitor is allowed to discharge is

a) CV b) CV2 c) CV

2/2 d) CV

2/4

97.The energy stored in a charged capacitor is

a) potential energy b) electrostatic potential energy

c) electromagnetic energy d) magnetic energy98.At the pointed ends of a conductor the curvature is

a) minimum b) maximum c) zero d) none of the above99.If R is the radius of curvature at a point, then curvature is

a) R b) R 2 c) 1/R d) 1/R

2

100.A lightning arrestor has a sharp spike for the following reason

a) it scares away birds b) charges leak away faster

c) it conducts heat quickly d) it reduces vibration

101.By enclosing the sphere of Van de Graaff generator in a gas filled steel

chamber at a very high pressure, which of the sphere is reduced

a) potential b) charge c) leakage of charge d) volume102.Which of the following cannot be accelerated using Van de Graaff

generator?

a) -particle b) electron c) proton d) deutron103.The electric potential energy of a system consisting of two charges is

directly proportional to the ……. of the two charges

a) sum b) difference c) product d) ratio

104.The force between two charges ,when they are separated by a certaindistance is ‘F’ N. When they are placed in medium, the distance of

separation is halved to get the same force. What is the relative

permittivity of the medium?a) 2 b) 4 c) 6 d) 5

105.The charge acquired by 5x1010

electrons

a) 3.204x10-19

C b) 4.806x10-19

C c) 1.602x10-19

C d) 8.01 x10-19

C

106.The electric potential at a point at a distance7.5cm from an electric

field25Vm-1

a) 1.75 V b) 1.875V c) 0.1875 V d) 17.5V

107.The permittivity of a medium having relative permittivity r =5a) 4.427x10

-11 Nm

2C

-2 b) 1.786 x10

-8 Nm

2C

-2

c) 53.12 x10-12

Nm2C

-2d) 1.8 x10

-9 Nm

2C

-2

108.The charges q1, q2 , q3 are lying within a closed surface and the charges

q4, q5 , and q6 are lying outside the surface. Then the electric flux


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linked with the surface is

a) = 1/0 (q1+q2 +q3) b) = 1/0 (q2+q3 +q6)c) = 1/0 (q1+q3 +q6) d) =1/0 (q2+q4+q6)

109.The electric flux inside a hollow metallic sphere of radius 5cm is

8x103 Nm

2 C

-1 .Find the amount of charge within the sphere

a) 44.2 nC b) 88.54 nC c) 70.8 nC d) 40x103C

110.The capacitance of air filled parallel plate capacitor is 4F. If thedistance between the plates is doubled and the space between the platesis filled with a dielectric material of dielectric constant 4 then its

capacitance is

a) 4F b) 32F c) 16F d) 8F111.Find the ratio of the effective capacitance of two capacitors 5F and

10F .When they are connected in parallel and seriesa) 2:9 b) 9:2 c) 10:3 d) 3:10

112.The potential at a point on the earth isa) zero b) positive c) negative d) infinity

113.6F is the charge given to a thin infinite plate of area 3cm2. Find itscharge density.

a) 2x10-2

Cm-2

b) 0.2x10-2

Cm-2

c) 1.8Cm-2

d) 5x10-2

Cm-2

114.Three capacitors are having equal capacitances 2F. Two of them areconnected in series and the third one is connected parallel with them.

What is the effective capacitance?

a) 6F b) 3F c) 2F d) 4F115.In the process of polarization of molecules , the dipole moment of …

are aligned in the direction of external electric field

a) permanent dipoles b) induced dipolesc) both (a) and (b) d) neither (a) and (b)

116.When an earthened conductor is moving away from a charged

conductor , then the potential of charged conductor

a) decreases b) increases c) does not change d) becomes zero

117.In a capacitor of capacitance 5F, the distance between the plates ishalved and filled with a material of dielectric constant 5, then itscapacitance is

a) 12.5F b) 2F c) 10F d) 50F118.When an earthened conductor moves towards a charged conductor ,the

potential of the charged conductor


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a) becomes zero b) increases c) decreases d) remains same

119.The electric field at a point on the surface of a hollow metallic spherea) depends on the radius of the sphere b) is zero

c) depends on the charge and radius of the sphere d) is constant

120.When a charged particle is moving against a repulsive force of electricfield then the ……. of the substance increases

a) kinetic energy b) electric potential energyc) mechanical energy d) magnetic energy

121.Addition nature of charge means, the total electric charge of a system is

equal to

a) the sum of positive charges b) the sum of negative charges

c) algebraic sum of all charges d) zero

122.Which is not the unit of electric flux?

a) Nm2C

-1 b) V m c) A m d) A m2

123.When a negative charge is given to a conductor , the conductora) gets decrease in the mass b) gets increase in its velocity

c) acquires an electric potential d) sends an electric current124.1volt/ metre equals

a) 1N b) 1Nm-1

c) 1NC-1

d) 1JC-1

125.Potential difference between the plates of a capacitor is 5.65V. If the

distance of separation is doubled , then potential difference is

a)1.13V b) 2.825V c) 1.4V d) 11.3V

126.In a capacitor if the value of the dielectric constant r is increased thenits capacitance willa)increase b ) decrease c) becomes zero d) becomes infinite

127.The effect due to charges outside the surface on the electric flux

a) increases the flux b) decreases the flux

c) does not change the flux d) reduces to zero128.SI unit of electric charge is

a) coulomb b) ampere metre c) volt second/ohm d) all the above

129.When two capacitors are connected in series to a source of emf , then

each one of them will have same

a) voltage b) electric field c) both (a) and (b) d) charge130.Two point charges placed at a distance ‘r’ in the air experiences a certain

force, then the distance at which they will experience the same force in

the medium of dielectric constant K is


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a) K r b) r/2 c) r/K d) r K131.Electron in an electric field of 9.11x10

6V m

-1 experiences an

acceleration of

a) 1.6x1016

ms-2

b) 1.6x1017

ms-2

c) 1.6x1018

ms-2

d)1.6x1019

ms-2

132.The work done in placing a charge of 8x10-18

C on a condenser of

capacity 100F isa) 3.1x10-28 J b) 4x10-10 J c) 32x10-32 J d) 10x10-32 J

133.Two parallel plates with 5 cm separation are at p.d. of 0.5KV. Forceacting on the electron between the plates is

a) 4.6x10-5

N b) 3.6x10-15

N c) 2.6x10-15

N d) 1.6x10-15

N

134.On moving a charge of 20 C by 2cm, 2J of work is done , then the potential difference between the points is

a) 0.5V b) 0.1V c) 8V d) 2V

135.The force of attraction between two charges +30x10-9

C and -20x10-9

C

separated by a distance of 0.20m is 5x10-5

N . find the relative permittivity of the medium

a) 2.7 b) 2.1 c) 2.2 d) 2.5

136.In hydrogen atom the ratio of electrostatic and gravitational force

electron and proton is

a) 1 b) 2.27x1039

c) 2.27x10-39

d) 2\

137.When a positive charge is brought nearer to a conductor the charge

induced at the far end of the conductor is

a) positive b) negative c) no charge d) unlike charge138.Theforce between two electrons separated by a distance r varies as

a) r 2 b) r c) r

-1 d) r

-2

139.Calculate the force between the two charges of value 1C and they areseparated by a distance of 1m in air is

a) 1/40 b) 8.854x10-12

c) 1/40r d) 40 140.Two point charges of equal magnitude are separated by 12 cm in air. An

attractive force of 90N acts on each charge. Then the two charges are

a) -12mC and -12mC b) +12mC and -12mC

c) +10mC and -10mC d) +6mC and -6mC

141.Two charges –q and +2q are placed at A and B respectively. Let AB =d.

At a point P between A and B , the potential is zero. Then the distanceAP is …..

a) d/4 b) d/3 c) d/2 d)2d/3

142.Two charged bodies of change +q, -3q are brought in contact and


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separated . The charge possessed by each body after separation.

a) –q , -q b) +q , -2q c) –q, +3q d) +q , +q143.An electric charge residing on s body produces

a) electric field b) magnetic field

c) both electric field and magnetic fieldd) neither electric field nor magnetic field

144.The lower comb of Van de Graaff generator is maintained at a +ve potential of

a) 10KV b) 10V c) 107V d) 100V

145.Over an equipotential surface , the electric field intensity is

a) everywhere tangential to the surface b) zero

c) everywhere normal to the surface

d) tangential at some places and parallel at some other places

146.Number of lines of force per unit area is proportional to the

\ a)magnitude of electric potential b) 1/0 c) magnitude of E d) magnitude of 0

147.The force between two charges in vacuum is 0.1N. What is the force if

the vacuum is replaced by a medium whose permittivity is 10 times

greater than that of vacuum.

a) 0.1N b) 0.01N c) 0.001N d) 0.0001N

148.The minimum value of the charge on any object cannot be less than

a) 1.6x10-19

C b) 3.2x10-19

C c) 4.8x10-19

C d) 1C

149.A stationary electric charge producesa) only electric field b) only magnetic field

c) both electric and magnetic field d) neither electric nor magnetic field

150.A surface enclosed an electric dipole , the flux through the surface isa) infinite b) positive c) negative d) zero

151.A positively charged glass rod attracts an object. The object must be

a) negatively charged b) positively chargedc) neutral d) either negatively charged or neutral

152.A charge q is located at the centre of a hypothetical cube. The electric

flux through any space of the cube is

a) q / 0 b) q / 20 c) q / 40 d) q / 60 153.If a glass rod is rubbed with silk , it acquires a positive charge because

a) protons are added to it b) protons are removed from it

c) electrons are added to it d) electrons are removed from it

154.Five balls numbered 1 to 5 are suspended using separate threads. Pairs


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(1,2),(2,4) and (4,1) show electrostatic attraction , while pairs (2,3) and

(4,5) show repulsion. Therefore, ball 1must bea) positively charged b)negatively charged c) neutral d)made of metal

155.A charge q1 exerts some force on a second charge q2. If a third charge q3

is brought near, then the force of q1 exerted on q2a) will decrease in magnitude b) will increase in magnitude

c)will increase if q3is of the same sign as q1 and will decrease if q1isopposite sign d) will remain unchanged

156.Two small spheres each carrying a charge q are placed r metre apart.

One of the spheres is taken around the other one in a circular path, the

work done will be equal to

a) force between them x r b) force between them x 2nr

c) force between them / 2nr d) zero

157.A hollow metal sphere of radius 5 cm is charged such that the potential

on its surface is 10V. The potential at the centre of the sphere isa) zero b) same as at a point 5 cm away from the surface

c) 10V d) same as at a point 25 cm away from the surface.158.A body can be negatively charged by

a) giving excess of electros to it b) removing some electrons from it

c) giving some protons to it d) removing some neutrons from it

159.Three charges +3q, +q and Q are placed on a straight line with equal

separation. In order to make the net force on q to be zero , the value of Q

will bea) +3q b) +2q c) -3q d) -4q

160.Charges reside on the

a) outer surface of the charged conductor b) inner surface of the charged conductor

c) inner as well as outer surface of the charged conductord) none of the above

161.The unit of electric permittivity 0 isa) farad/metre b) volt / metre c) coulomb / farad d) coulomb/m

2

162.There are two charges +1C and +5C separated by a certain distance d.The ratio of forces acting on them will bea) 1:5 b) 1:1 c) 5:1 d) 1:25

163.The potential at any point inside a charged sphere is

a) zero b) smaller than the potential on the surface


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c) greater than the potential on the surface

d) same as potential on the surface164.Two conducting spheres of radii r 1 and r 2 are equally charged . The ratio

of their potentials is

a) r 12 / r 2

2 b) r 2

2 / r 1

2 c) r 1 / r 2 d) r 2 / r 1

165.Two condensers of capacity C1 and C2 are connected in parallel . If a

charge q is given to the assembly, the charge gets shared. The ratio ofthe charge on the condenser C1 to the charge on the condenser C2 is

a) C1 / C2 b) C2 / C1 c) C1C2 d) 1 / C1C2

166.If a capacitor of capacitance 55 pF is charged to 1.6V , then the number

of electrons on its negative plate is

a) 55x107 b) 5.5x10

7 c) 550x10

7 d) 0.55x10

7

167. If total charge of the decay of an element is 92 e , then the total charge after

decay is

a) 41 e b) 91 e c) 92 e d) 184 e168.If F and Fm are the force between two charges in air and medium then the rat

of F/Fm is calleda) permittivity b) permeability c) charge d) relative permittivity

169. The total flux over a closed surface of charge q is

a) 4q b) 36 x 109 q c) 9 x 109 q d) 4 x 109 q170. If a positively charged plate is brought nearer to a negatively plate,

then the potential difference between them will

a) increase b) remain the same c) become zero d) decrease171.If n identical capacitors each of capacity C are connected in series , then its

equivalent capacity is

a) n C b) 1/n C c) n / C d) C / n172.The dielectric constant of a substance is 4 .The permittivity of that substance

is a) 4 b) / 4 c) 4 0 d) 0 / 4173.The capacitance of a parallel plate is maximum when the region between the

plates are

a) completely filled by dielectric material b)partially filled by dielectric mater

c)completely filled by air d) completely filled by conducting material

174.If the work done for moving a unit positive charge from a point X to another

point Y is zero , then

a) potential at X is less than potential at


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b)potential at Y is less than potential at X

c) potential at X is equal to potential at Yd) potential at X is positive whereas the potential at Y is zero

175.The imaginary surface drawn for determining the field at a point due to infinit

plane sheet of charge isa) spherical b) plane c) cylindrical d) cubical

176.The surface charge density is more ata)less curvature b)greater curvature

c) plane surface d)greater radius of curvature

177.The potential developed in the Van de Graff generator is used for

a) domestic current supply b) industrial current supply

c) nuclear reaction d) nuclear fusion

178.As the thickness of dielectric increases between the two plates then the

capacity of the condenser

a) decreases b) increases c) constant d) becomes zero179.If the change of potential with respect to distance is given as V = r

2-3r-5 then

find electric field intensity at a distance 5 unitsa) 2 units b) 7 units c) 3 units d) 5 units

180.When air medium in capacitor is replaced by a medium of dielectric constant

the capacitance

a) decreases r times b) remains the samec) increases r times d) increased by r

2 times

181.A certain region of space isolated from external electric field is known asa) electrostatic induction b) electrostatic shielding

c) electrification d) charging

182.In Van de graff generator , the belt acquires charges from comb , bya) electrostatic induction b) electromagnetic induction

c) conduction d) action of points

183.When a dipole is placed anti parallel to the electric field it has

a) no potential energy b) minimum potential energy

c) maximum potential energy d) finite potential energy

184.The electric field due to a helium nuclei at a point on its orbit of radius 0.25A

is

a) 4.608x103 NC

-1 b) 4.608x10

-8 NC

-1 c) 4.608x10

12 NC

-1 d) none

185.The electric flux depends on


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a) location of charge b) value of charge

c) charge outside Gaussian surface d) both location and value186.During lightning it is better

a) to stand under tree b) to stand in a open space c) to run d) to sit inside a bu

187.When a dielectric is introduced in a parallel plate capacitor ,the inducedelectric field

a) same direction as applied field b) perpendicular to applied fieldc) opposite to applied field d) 45

0 with field

188.When ‘n’ capacitors of equal capacitances are connected in parallel and series

the ratio of effective capacitance is

a) 1;n2 b) n:1 c) n

2:1 d) 1:n

189.Two charges 24C each of same polarity are separated by 200Cm.The forceacting on another 4C charge placed at the midpoint on the line joining twocharges be

a) zero b) 31.44 N c)12.88N d) 44.32N190.The force between two charges in air is F. This force becomes 13/25 F when

placed in a medium at the same distance. The r of medium isa)13/5 b) 14/5 c) 25/13 d) 15/4

191.Two charged spheres of radius 15 cm and 20cm are connected by a thin wire.

No current will flow ifa) they have the same potential b) they have different potential

c) they have equal charge d) they have unequal charge

192.If the radius of a conducting solid and conducting hollow sphere are the samwhich one can hold greater charge

a)solid sphere b) hollow sphere c) both will hold equal charge

d) hollow sphere will hold half the charge of solid sphere.193.The dielectric constant K of an insulator can be

a) b) zero c) -2 d) 6194.In the direction indicated by an electrostatic field line

a) the electrostatic field strength must increase

b) the electrostatic field strength must decrease

c) the electrostatic potential must increased) the electrostatic potential must decrease

195.A proton is moved between two points whose potential difference is 30V. Thekinetic energy acquired in eV is

a) 30 eV b) 10 eV c) 20 eV d) 40 eV


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196.An infinite charged plane sheet produces a field of 2x105 NC

-1 at a distance of

5 cm. The surface charge density is

a) 3.54x10-10

Cm-2

b) 0.35x10-6

Cm-2

c)3.54x10-6

Cm-2

d) 3.54 Cm

-2

197.Charge per unit length is called

a) charge density b) surface charge densityc) linear charge density d) electric intensity

198.To eliminate sparking in the ignition system of automobile engines we use

a) inductors b) resistors c) engine oil d) capacitors

199.Xerox copying machine is working on the principle of

a) electric force b) magnetic force

c) electrostatic force of attraction d) centripetal force

200.The electric potential energy of two point charges is not equal to

a) the work done to assemble the charges b) force between the two charges

c) work done in bringing each otherd) work done in bringing a charge from infinite distances

II. IMPORTANT UNITS

1.The unit of Coulomb force between the two point charges is ……….

2.The unit of permittivity is ……….3.The unit of relative permittivity is ……….

4.The unit of electric charge is ……….

5.The unit of electric field intensity is ……….6.The unit of electric dipole moment is ……….

7.The unit of torque is ……….8.The unit of electric potential difference is ……….

9.The unit of electric flux is ……….

10.The unit of linear charge density is ……….

11.The unit of surface charge density is ……….12.The unit of capacitance is ……….

13.The practical units of capacitance are ………. and ……….

14.Farad is equal to ..........

15.The unit of 1/40 is ……….


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III. STANDARD VALUES

1.The charge of an electron is ….

2.Permitivity of free space 0 is ….3. The value of 1/40 is ……….4.Relative permittivity of air is ……

5. Permittivity of air is ……6.The ratio of electrostatic force to gravitational force of attraction between anelectron and a proton is …..

IV. IMPORTANT FORMULAE

1.Force between the two charges is………..

2.Relative permittivity(dielectric constant ) is …………

3.Amount of charge is ………….4.Relation between the force in air and medium is ………..

5.Relation between electric field and force is ………….

6.Electric field due to point charge is ……………

7.Electric dipole moment is ………….

8.Electric field due to an electric dipole at a point on its axial line is …….

9. Electric field due to an electric dipole at a point on the equatorial line is …

10.Torque on a dipole placed in a uniform electric field is ……..

11.Electrical potential energy of a dipole is ……..12.Electric potential energy of a point charges is …..

13.Electrical potential at a point due to point charge is ……….

14. Electrical potential at a point due to an electric dipole is ……….15.Electric flux according to Gauss’s law is …………

16.Electric field due to plane sheet of charge q is ………

17.Electric field at a point between parallel sheet of charge is ………18.Electric field due to an infinite long straight charged wire is …….

19.Electric field due to uniformly charged spherical shell at a point outside the she

is ……

20. Electric field due to uniformly charged spherical shell at a point on the surface

of the shell is ……..21.Electric field due to uniformly charged spherical shell at a point inside the shel

is…..

22.Capacitance of a conductor is ………..


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2.State Coulomb’s law in electrostatics.

3.State Gauss’s law.4.What is known as electrostatic induction?

5.What is known as electrostatic shielding?

6.What is known as action of points?7.What is the principle of capacitance?

3.USES.(APPLICATIONS)

1.Mention the applications of capacitor.

2.What are the uses of electrostatic devices?

3.What is the use of lightning conductor?

4.State the use of Van de Graff generator.

5.State the application of electrostatic force of attraction and repulsion.

4. PROPERTIES(CHARACTERISTICS)

1.Give any three properties of electric lines of force.

5.REASONING QUESTIONS

1.Why is it safer to be inside a car than standing under a tree during

lightning?

6.DISTINGUISHING AND DIFFERENTIATING QUESTIONS

1.Distinguish between electric potential and potential difference.2.Distinguish between conductors and insulators.

3.Distinguish between polar and non-polar molecules

4.State the differences between electric field intensity and electrical potential

7.THEORY QUESTIONS

1.What is meant by quantization of electrical charge?

2.What is permittivity and relative permittivity? How are they related.

3.What does an electric dipole experience when kept in a uniformelectric field and non – uniform electric field.


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4.Explain the working of microwave oven.

5.What is non polar molecule? Give examples.6.What is polar molecule? Give examples.

7.What is the effect of placing a dielectric inside a parallel plate

capacitor?8.How can you increase the capacitance of a parallel plate capacitor.

VI. THREE MARK PROBLEMS

1.A polythene piece rubbed with wool is found to have a negative charge of

3x10-7

C .Calculate the number of electrons it has gained.

2.A glass rod rubbed with silk acquires a charge of + 8 x 10-12

. Find thenumber of electrons it has lost.

3.Two positive charges of 5C and 3C are kept at a distance of 3m from eachother in vacuum. What is the force between them?

4.When two point charges +6c and -5C experiences a force of 2.7x1011

N.

Find the distance between them.

5.Two point charges at a certain distance experiences a force of 5N . Each

charge is doubled in magnitude and distance between the is halved.

Calculate the new force .6.Two spheres charged with equal but opposite charges 10 cm apart in a

medium of relative permittivity 9 experiences a force of 103 N. Calculate

charge on each sphere.7.The electrostatic force between two point charges kept at a distance d

apart, in a medium r =6, is 0.3N. Calculate the force between them at thesame separation in vacuum.

8.The force of attraction between the two point charges increases from 5N to

50N when the dielectric medium is replaced by air. Find the relative

permittivity.9.Calculate the permittivity of a dielectric of dielectric constant 6.

10.Two point charges+10C and -10C are placed 5mm apart.Calculate the electric field at a point 5 cm from its centre along the

equatorial line.

11.Two point charges+10C and -10C are placed 5cm apart.


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Calculate the electric field at a point 10 cm from its centre along

the axial line.12.The potential at a point 50 cm from the centre of an electric dipole

of dipole moment 10-5

C m is 1.8x105V. Find the angle made by the

line joining the point and the centre of the dipole with the axis ofthe dipole.

13.The potential difference between two points 2.5 cm apart in anelectric field is 10V. Find the electric field intensity between these

points.

14.Calculate the potential at a point due to a charge of 100C at adistance of 9 m .

15. Calculate the amount of work done in bringing a charge of 2x10-9

C

from infinity to a point having potential of4x104V

16.An infinite charged plane sheet produces a field of 2x105

NC-1

at adistance of 5 cm. Find the surface charge density.

17.A uniformly charged conducting shell of 2 cm diameter has a

surface charge density of 80C m-2.Find the charge on the shell.18.A spherical shell of radius 2 cm has a charge of 4.5x10

-12.Calculate

the electric field at a point 3 cm from its centre.

19.Electric field intensity is 400Vm-1

at a distance of 2m from a point

charge. At what distance it will be 100Vm-1

.

20.Two point charges +4q and +q are placed 30 cm apart. At what point on the line joining them the electric field in zero?

21.Calculate the electric field intensity at a point 20 cm away from a

point charge of 2x10-5

C22.Calculate the magnitude of the force acting on a charge of 2x10

-10 C

placed in a uniform electric field of 10Vm-1

.

23.A charge experiences a force of 0.02N in an electric field ofintensity 5x10

4 Vm

-1.Find the value of the charge.

24.Two charges +2.5C and -2.5C are separated by a distance of 5 cm.Find the electric dipole moment

25.An electron experiences a force of 1.82x10-14

N in an electric field .

Calculate the acceleration produced on it.26.An electric dipole with dipole moment 4x10

-9C m is aligned at 30

0

with the direction of a uniform electric field of magnitude 5x104 NC

-1.

Calculate the magnitude of the torque acting on the dipole.


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27.A molecule having dipole moment 3.4x10-30

C m is placed in an

electric field of 2x104 N C

-1.Calculate the maximum torque that can

act on the molecule.

28.When a point charge of 6C is moved between two points in anelectric field, the work done is 1.8x10

-5J.Find the potential difference

between the two points.

29.The work done in moving 4C charge from one point to another inan electric field is 0.012 J. Find the potential difference betweenthem.

30.Calculate the potential energy of two equal negative point charges

of magnitude 2C placed one metre apart in air.31.A dipole of dipole moment 8x10

-10 C m is inclined at an angle 60

0

with an electric field of 0.9x10-4

N C-1

. Calculate its potential

energy.

32.The equivalent capacitance of two capacitors in series is 1.5F. Thecapacitance of one of them is 4F. Find the value of capacitance ofthe other.

33.A capacitor of capacitance 6F is connected to a 100V battery.Calculate the energy stored in the capacitor.

34.The capacitance of a parallel plate capacitor increases from 5F to50F when a dielectric is filled between the plates. Find the permittivityof the dielectric.

35.Three capacitors of capacitances 1F, 2F and 3F are connected inseries. Find the effective capacitance of the capacitors.

36.Calculate the charge that can be stored in a 50F capacitorconnected to a source of potential difference of 20 V.

37.Calculate the capacity of a parallel plate capacitor consisting of two

circular plates of area 400cm2 and separated by a distance of 2mm

with air as medium.

38.Calculate the capacity of a parallel plate capacitor consisting of two

circular plates of area 80cm radius and separated by a distance of1mm mica plate of dielectric constant 6 .

39.If a sphere surrounded by air is dipped in a liquid, its capacitance

changes from 4 pF to 12 pF . What is the dielectric constant.

40.Three capacitors of capacitances 0.5F, 0.3F and 0.2F areconnected in parallel . Find the effective capacitance of the


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capacitors.

41.Calculate the work done in giving a charge of 8x10-18

C on a

condenser of capacity 100F.

VII. FIVE MARK QUESTIONS.

1.State Coulomb’s law in electrostatics and State its vector form.2.List the properties of electric lines of force.

3.Define electric field at a point. Give its unit and obtain an expression for theelectric field at a point due to a point charge.

4.Derive an expression for the torque acting on the electric dipole when placed in

uniform field.5.Derive an expression for electric potential energy of an electric dipole in an

electric field.

6.Write a note on equipotential surface.7.Explain the method of charging by induction.

8.Explain the distribution of charges on a conductor and action of point.

9.Derive an expression for electric field due to two parallel charged sheets.

10.Deduce an expression for the equivalent capacitance of capacitors connected in

series.

11.Deduce an expression for the equivalent capacitance of capacitors connected in parallel.

12.Prove that the energy stored in a parallel plate capacitor is q

2

/2C or 1/2 CV

2

VIII.TEN MARK QUESTIONS

1.Derive an expression for electric field due to an electric dipole at a point on itsaxial line

2. Derive an expression for electric field due to an electric dipole at a point along

the equatorial line .

3.Derive an expression for electric potential due to an electric dipole. Discuss the

special cases.4.State Gauss’s law. Applying this, calculate electric field due to (i) an infinitely

long straight wire with uniform charge density (ii) an infinite plane sheet of

charge of q.5.Explain the principle of capacitor. Deduce an expression for the capacitance of

the parallel plate capacitor.


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6.What is dielectric? Explain the effect of introducing a dielectric slab between th

plates of parallel plate capacitor.7.State the principle and explain the constructions and working of Van de Graaff

generator.

8.Determine electric field due to uniformly charged spherical shell at a point (i) oside the shell (ii) on the surface (iii) inside the shell.

KEY-LESSON-1

1 c 21 a 41 a 61 d 81 c 101 c 121 c 141 b 161 a 181 b

2 d 22 a 42 b 62 b 82 a 102 b 122 d 142 a 162 b 182 d

3 c 23 a 43 b 63 b 83 c 103 c 123 c 143 a 163 d 183 c

4 d 24 a 44 a 64 d 84 d 104 b 124 c 144 a 164 d 184 c

5 d 25 a 45 c 65 c 85 a 105 d 125 d 145 c 165 a 185 b

6 d 26 a 46 b 66 a 86 b 106 b 126 a 146 c 166 a 186 d

7 d 27 a 47 d 67 b 87 a 107 a 127 c 147 b 167 c 187 c

8 b 28 c 48 c 68 a 88 c 108 a 128 d 148 a 168 d 188 c

9 d 29 c 49 c 69 c 89 c 109 c 129 d 149 a 169 b 189 a


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10 d 30 a 50 b 70 d 90 c 110 d 130 c 150 d 170 d 190 c

11 c 31 c 51 d 71 c 91 c 111 b 131 c 151 d 171 d 191 a

12 c 32 b 52 d 72 a 92 d 112 a 132 c 152 d 172 c 192 c

13 b 33 b 53 d 73 a 93 b 113 a 133 d 153 d 173 a 193 d

14

d34

b54

c74

c94

d114

b134

b154

c174

c194

d15 c 35 d 55 b 75 c 95 c 115 c 135 a 155 d 175 c 195 a

16 d 36 b 56 b 76 c 96 c 116 b 136 b 156 d 176 b 196 c

17 d 37 a 57 d 77 c 97 b 117 d 137 a 157 c 177 c 197 c

18 d 38 b 58 b 78 b 98 b 118 c 138 d 158 a 178 b 198 d

19 b 39 b 59 c 79 c 99 c 119 c 139 a 159 a 179 b 199 c

20 d 40 b 60 a 80 d 100 b 120 b 140 b 160 a 180 c 200 b

2.CURRENT ELECTRICITY.

1.Super conductors have zero a) resistance b) conductance c) permeability d) permittivity

2.The reciprocal of the slope of the graph drown between V&I for steady

current in a conductor gives

a) resistance b) conductance c) resistivity d) conductivity

3.The current always flows from

a) +veto –ve b) –ve to +ve c) –ve to –ve d) +ve to +ve

4. The electrons always flows from

a) +veto –ve b) –ve to +ve c) –ve to –ve d) +ve to +ve5.A car battery has emf 12 volt and internal resistance 5x10

-2 .If itdraws 60ampere current the terminal voltage of the battery will be

a) 15V b) 3V c) 5V d) 9V

6.Resistance of a metal wire of length 10cm is 2. If the wire isstretched uniform to 50 cm the resistance is


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a)25 b) 10 c )5 d) 50 7.The ratio of the resistance of conductor at 15

0C to resistance at

temperature 37.50C is 4:5.What is the temperature co-efficient of

resistance of the conductor.

a) 1/75 b) 2/51 c) 2/75 d) 1/50

8.Ten identical wires (same material, same length and same cross

section)each having a resistance of one ohm are joined in parallel ,thecombination has a resistance of

a) 10 b) 1 c) 0.1 d)0.01 9.Two wires of each length 1.3m and 2.6m which are having radius of

0.32mm and 0.16mm respectively made up of same material. The ratioof the resistances of wire is

a) 8:1 b) 1:8 c) 1:4 d) 4:1

10.The potential developed between two ends of the conductor is

25V,2A current flows through it , the conductance of the conductor isa) 80 mho b) 80 milli mho c) 80 micro mho d) 40 mho

11.The resistance of the conducting wire is 10 , the resistance ofanother wire whose length is halved and the area is doubled made up

of same material is

a) 10 b) 40 c) 2.5 d)25 12.A charge of 60C passes through an electric lamp in 2 minutes .Then

the current in the lamp is

a) 30A b) 1A c) 0.5A d) 5A13.A resistance of wire is cut into 4 equal parts and all the parts are

connected in parallel. The ratio of the effective resistance to the

original resistance isa) 2:1 b) 1:2 c) 1:4 d) 4:1

14.The end error in meter bridge can be eliminated by

a) using thick copper strips b)interchanging two resistances in the gaps

c) adjusting the balancing point near midpoint d) both (b) and (c)

15.Meter bridge is used toa) compare two resistances b) find specific resistance

c) determine temperature coefficient d) all these

16.Actual resistance of standard 2 resistor is 2.1. The resistance to beconnected to make it standard is

a) 0.1 in series b) 42 in parallel c)0.1in parallel d)4.2 in series


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17.Emf’s E1 and E2 of two given cells can be compared by using

potentiometer with primary circuit of Emf E if

a) E1 E2 b) E1, E2 E c)E1 E2 d) E1,E2 E

18.In a net work with constant source of emf , if more resistances are

added in series , the power supplied by the source

a) increases b) remains samec) decreases d) either increased or decreased

19.In a net work with constant source of emf , if more resistances are

added in parallel , the power supplied by the source

a) increases b) remains same

c) decreases d) either increased or decreased

20.The emf of Lechlanche cell is 1.5V. When a resistance 5isconnected, the current in the circuit is 0.25A, the internal resistance is

a) 0.5 b) 1.5 c) 1.0 d) 2.0 21.In a potentiometer,the balancing point of a cell of emf 2.5V is 75 cm.

By connecting another cell, if the balancing point is decreased by

15 cm , emf of the cell is

a) 4V b) 3V c) 2V d) 1V

22.An incandescent lamp is operated at 250V.If the bulb is rated at

125W, its resistance must be

a)1K b) 0.5K c) 2.0K d)2.5K 23.Two identical resistances are first connected in series and then in

parallel to a source of emf 0.3V , the ratio of power suppliedrespectively is

a) 4:1 b) 1:2 c) 1:4 d) 2:1

24.Total current of 3A is passed through the combination of twoidentical resistances are first connected in series and then in parallel,

the ratio of power supplied respectively is

a) 4:1 b) 1:2 c) 1:4 d) 2:1

25.Free electrons are very loosely attached to the

a) nuclei b) protons c) atoms d) neutrons26.Expression for electric resistance(R) is

a) R=mL / nAe2 b) R=nL/ mAe2 c)R= nAe2/mL d)mLV/ nAe2

27.The conductivity of a material is obtained by the formula

a) = RA/ l b) =l A/R c) = l /RA d) =A/R

28.Discontinuous change in specific heat of material occurs at


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a) transition temperature b) high temperature

c) 0K d) room temperature29.If the resistance of a material increases with increase in temperature

then its temperature coefficient of resistance is

a) zero b) negative c) positive d) none of these.30.Due to aging , the internal resistance of a cell

a) increases b) decreases c) does not change d) becomes zero

31.The condition for bridge balance in Wheatstone’s bridge isa) P/S = R/Q b) PR = QS c) PS = QR d) PQ = RS

32.If a charge of 1C passes through an electrical equipment in 10 s ,

then the current flowing through is

a) 0.5A b) 1A c) 0.1A d) 10A

33.The marking at the bottom of a tape recorder are as follows

9V,450mA. The net resistance of the system is

a) 20 b) 200 c) 1/20 d) 2 34.An electrical instrument of resistance 30 is operated at 240V. The

power is

a) 240W b) 1290W c) 920W d) 1920W

35.The number of electrons flowing per second through a conductor ,

when a current of 3.2A flows through it isa) 2x10

19 b) 3x10

18 c) 6.25x10

18 d) 6.25x10

19

36.A 1.15 KW , 230V water heater can draw a currenta) 0.2A b) 2A c) 5A d) 0.5A37.If charge per unit volume of a conductor is 600C and the current

density is 1.2Am-2

, then the drift velocity of the electrons is

a) 0.2x10-2

m/s b) 7.2x10-3

m/s c) 200 m/s d) 5x10-3

m/s

38.Three resistances of values 10, 2 and 3 are connected to formthe sides of a triangle AB,BC and CA respectively . The effective

resistance between A and B is

a) 3.33 b) 2.33 c) 3.5 d) 3.9 39.A cell of emf 9V and internal resistance 1 is connected to an

external resistance of 8, the potential difference across the cell isa) 9V b) 1V c)6V d) 8V

40.In Wheatstone’s bridge , under bridge balance condition the four

resistances of the four arms in cyclic order is


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a) 5,10,4,8 b) 5,10,8,4 c) 5,8,10,4 d) 5,4,8,10

41.The drift velocity does not depend upona)the magnetic field b) the mass of the electron

c)the charge of the electron d)the relaxation time

42.When the diameter of a conductor is doubled , its resistancea) decreases twice b) decreases four times

c) decreases sixteen times d) increases four times43.A cell of emf 2.2V sends a current of 0.2A through a resistance 10.

The internal resistance of the cell is

a) 0.1 b) 1 c) 2 d) 1.33 44.The electrical resistivity of a thin copper wire and a thick copper rod

are respectively 1m and 2 m . Thena) 1 2 b) 2 1 c) 1 = 2 d) 2/1=

45.The brown ring at one end of a carbon resistor indicates a tolerance

ofa) 1 % b) 2 % c) 5 % d) 10 %

46.Length of the wire with resistance ‘R’ is stretched for 3 times of itsoriginal length , now the resistance becomes

a) 3R b) 1.5R c) 3R 2 d) 9R

47.As the temperature increases , the conductance of a conductora) increases b) decreases c) does not change d) becomes infinity

48.The ratio of the effective resistance of two 2 resistance when they

are connected in parallel and in seriesa) 1:4 b) 4:1 c) 1:2 d) 2:1

49.Mobility is proportional to

a) inversely to the electric field b) directly to the mass of the electron

c) inversely to the drift velocity d) inversely to the charge

50.The amount of current flowing through a conductor is directly proportional to

a) the number of electron per unit volume b) the drift velocity

d) the cross sectional area of the conductor d) all the above

51.The magnets used to levitate the trains from the railsa) permanent electromagnets b) strong magnetic substance


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c) a magnetic field with varying frequency

d) super conducting magnets52.The special features of carbon resistor

a) small in size b) stable c) cheaper d) all these

53.The specific resistance of a conductor is 5x10-5 m . If its length is

elongated 4 times then its specific resistance isa) 20x10-5 m b) 1.25x10-5 m c) 5x10-5 m d) 8x10-4 m

54.A conductor of length 2 m and area of cross section 6 mm2 has

specific resistance 3x10-6 m . Then its resistance is

a) 4 b) 1 c) 0.1 d) 0.9

55.A circuit consists of two resistances R 1& R 2 connected parallel to

each other. When a current I flows through the circuit , then the

amount of current flowing through R 1 is

a) I1= I(R 2/ R 1+R 2 ) b) I1= I(R 1/ R 1+R 2 )c) I1= IR 2/ R 1-R 2 ) d) I1= I(R 1/ R 1+R 2)

56.The resistivity of a conductor is 40x10-6m . Then its conductivity is

a)25x105mhom

-1 b)2.5x10

4mhom

-1c)25x10

-5mhom

-1 d)25x10

-4mhom

-1

57.Electrolytes are

a) the liquids which allow the ions to move through them

b) the liquids wherein charged ions can be dissociate in opposite

direction c) both (a) , (b) are correct d) (a) is correct, (b ) is wrong

58. The cells from which the electric energy is derived by irreversiblechemical reactions are

a) primary cell b)secondary cell c)Daniel and dry cell d)both(a)& (c)

59.According to Faraday’s laws of electrolysis , when charge is passing

through the electrolyte , the mass of the substance liberated at theelectrode depends on

a) current b) charge c) time d) all these

60.Current is

a) the number of electrons crossing per second at a point in a conductor b) rate of flow of chargec) a scalar quantity d) all the above

61.The direction of conventional current is the direction

a) of motion of electrons b) opposite to the motion of positive charge

c)of random motion of electrons d)opposite to the motion of electrons

62.In a carbon resistor it consists of yellow, yellow and black rings at


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one end and silver ring at the other end, then the resistance is

a)44000+10 % b) 440 +10 % c) 44 +10 % d) 4400 +10 % 63.The appropriate material to be used in the construction of resistance

boxes out of the following is

a) copper b) iron c) manganin d) aluminium

64.When two resistances connected in series and parallel their effective

resistances are 12 and 8/3 then the individual resistances area) 6, 6 b) 3 , 9 c) 7 , 5 d) 8 , 4

65.The resistance of a wire of length is 6 . If its length is elongated as2L, then its resistance is

a) 6 b) 12 c) 24 d) 48 66.In a Wheatstone bridge P=15 , Q= 35 , R=60, then S=?

a) 80 b) 85 c) 105 d) 140 67.When 1.6 A current is flowing through a conductor in one minute,

then the number of electrons moving in it is

a) 60x1019

b) 3x1020

c) 6.25x1018

d) 1.6x10-19

68.Two wires of equal length are having the radius ratio 1:2, then theratio of their resistances is

a) 1:4 b) 4:1 c) 1:2 d) 2:1

69.When 400mA current flowing through a wire of resistance 25, then

the potential difference between the ends of the wire is

a) 5V b) 1V c) 10V d) 12.5V

70.The substance which have negative temperature coefficient ofresistance

a) carbon b) ebonite c) Germanium d) all the above

71.A cell having emf 1.5V is connected with a resistor of 1000. What is its power?

a) 2.25 mW b) 1.5W c) 225W d) 150mW

72.The substances like carbon and ebonite are

a)having negative temperature coefficient of resistance

b) conducting materials c) electrolytes

d) having low temperature coefficient of resistance

73.The relation between current density and drift velocity

a) J=neA/ Vd b) Vd=Jne /A c) Vd = J / ne d) J = Vd e /A


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74.When the length of a conductor is cut into two equal parts , one of its

resistance is …… and its resistivity is ……a) halved; halved b) halved; increased twice

c) increased twice ; halved d) halved ; having no change

75.The flow of free electrons by emf in a definite direction producesa) current b) resistance c) drift velocity of electron d) all the above

76.In the case of carbon, when temperature increases the resistance

a) increases b) decreases c) remains the same d) becomes zero

77.An electric bulb shows 550 resistance when a potential of 220 V isapplied to it.The amount of current flowing through it is

a) 0.5 A b)2.5 A c) 0.4 A d) 5A

78.Ohm's law is true for

a) metals only b) semiconductors only

c) both for metals and semiconductors

d) neither metals nor semiconductors79.In a Wheatstone's network if the cell and galvanometer are inter

changeda) the condition for null deflection remains same as before

interchanging b) null deflection can never be obtained

c) the condition for null deflection will be disturbedd) the current in all branches becomes zero

80.Current in super conducting wire can flow

a) with change in magnitude b) with change in directionc) without change in magnitude and direction

d) with change in magnitude and direction

81.The effective resistance of two resistance connected in parallel is

2.4If the second resistance is 1.5 times the first one, theresistances are

a) 4 and6 b) 2 and3 c)3and4.5 d) 6 and9

82.If the balancing point lies at the centre of the meter bridge wire andthe resistance in the resistance box is 5 , then the unknownresistance is

a) 5 b) 10 c) 2.5 d) 083.The value of resistance having code brown, red and orange is

a) 12K b120 c) 1.2 K d) 12


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84.Metre bridge consists of a wire of higha) temperature coefficient and low specific resistance

b) low temperature coefficient and high resistance

c)low specific resistance and hgih temperature coefficientd) high specific resistance and low temperature coefficient

85.Ohm's law is valid when ............. is constanta) voltage b) temperature c) resistance d) area

86.The power generated in a resistor of 5k with a current flow of50 mA is

a) 12.5W b) 250W c) 1.25MW d) 2.5 MV87.The drift velocity of electrons having a charge of 12.8x10

9C and

current density of 2x106 A/m

2 is

a) 1.56 m/s b)15.6x10-5

m/s c) 156x10-5

m/s d) 0

88.Resistance of a material at 00

C and 300

C are respectively40and90. Its temperature coefficient of resistance is a) 0.4617 /

0C b) 0.04617 /

0C c) 0.005 /

0C d)24 /

0C

89.The resistance of a conductor of unit length having unit area of cross

section is

a) resistivity b) conductivity c) conductance d) capacitance

90.Two copper wire of length 1m and 9m have equal resistances. Then

their diameters are in the ratio of

a) 3:1 b) 9:1 c) 1:9 d)1:391.Resistivity of mercury is zero at

a) 2.4 K b) 4.20C c) 4.2 K d) 2.4

0 C

92.A material with negative temperature coefficient of resistance iscalled

a) metal b) alloy c) thermistor d) thermometer

93.What is the minimum number of bulbs each marked60 W, 40 V , thatcan work safely when connected in series with a 240 V main supply?

a) 2 b) 4 c) 6 d) 8

94.In secondary cells the process of reproducing active materials is

called

a) charging b)discharging c) specific gravity d) internal resistance95.Discontinuous change in specific heat of a material occurs at

a) transition temperature b) high temperature

c)room temperature d) 0 K


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96.If two resistors of resistance 200 and 0.1k are connected in seriesthen the effective resistance of the system is

a) 200.1 b) 300 c) 201 d) 2.1 k 97.The system may be used to launch satellites directly into orbit from

earth , without the use of rockets is

a) solid propellant system b) liquid propellant system

c) super conducting magnetic propulsion systemd) electric propellant system

98.If the internal resistance of the electric cell increases, the delivered

electric current

a)decreases b)increases c)first increases and then decreases d) zero99.If charge per unit volume of a conductor is 6mC and the current

density is 1.2Am-2

, then the drift velocity of the electron is

a) 0.2x10-3

m/s b) 7.2x10-3

m/s c) 200 m/s d) 5x10-3

m/s

100.The resistance of a conductor is 5 at 500C and 6 at 1000C . Then theresistance at 0

0C is

a) 0 b) 3.5 c) 4 d) 8 101.The value of electrical energy equal to 1KWhr is

a) 1 unit b) 1 joule c) 1 volt d) 1 ampere

102.In a metre bridge , with a standard resistance of 5 ohm in the right

gap, the ratio of balancing length is 3:2. The value of the other

resistance is

a) 10/3 b)10 c)15/2 d)3/5

103.The balancing lengths of two cells are 250 cm and 750 cm

respectively , in a potentiometer experiment. If the emf of the first

cell is 2 V , the emf of the second cell isa) 6V b) 4V c) 2/3 V d) 3/2 V

104.A 750W power iron box is used for 4 hours. If the cost per unit is 75

paise, the total expense is

a) Rs.22.50 b) Rs.5.25 c) Rs2.25 d) Rs3.00105.For what time a current of 1.5A pass through a copper-voltameter

to deposit 1g of copper?(Z=3.3x10-4

g/C)

a) 25minute b) 50 minute c) 34minute d) 40 minute

106.Silver and zinc voltmeters are connected in series and same current

is passed through both of them for same time. If x kg of Ag is


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liberated, then amount of Zn liberated in kg will be very near to

(chemical equivalent of Zn = 33;chemical equivalent of Ag=108)a) x b)x/5 c) x/3 d) x/2

107.If J is the current density then the power transferred per unit volume

in joule in a resistor of resistivity isa) J

2/ b) J2 c) J d) J22

108.In hydrogen atom, electron moves in an orbit of 0.5A0 with a speed

of 2.2x106 m/s. What is equivalent current?

a) 1.25A b) 1.12A c)1.12mA d)1.12pA109.The resistance of wire is R ohm. What will be new resistance ,if it

is stretched uniformly n times its original length

a) nR b) R/n c) n2R d) R/n

2

110.If R 1 and R 2 be the resistances of the filaments of 200W and 100W

electric bulbs operating on 220V, thena) R 1=R 2 b) R 1=2R 2 c) R 2=2R 1

d) there is no relation between R 1and R 2

111.A voltmeter 100V range is of 9000 ohm resistance and another

voltmeter of range 80v has a resistance of 11000 ohm. This

combination is connected across 120v. The reading of voltmeter of100v range will be

a) 54V b) 44 V c) 66V d) 56V

112.The ratio of resistance to conductance isa) 1:R b) R:1 c) 1:R

2 d) R

2:1

113.The ratio of conductance to resistance is

a) 1:R b) R:1 c) 1:R 2 d) R

2:1

114.The ratio of resistivity to conductivity is

a) 1: b) :1 c) 1: 2 d) 2 :1115.The temperature coefficient of resistance is positive for

a) aluminium b) carbon c) germanium d) none of the above

116.Which one of the following is the best material for making

connecting wires?a) manganin b) constantan c) copper d) nichrome

117.Which one of the following is the best material for making standardresistance wire?

a) tungsten b) constantan c) copper d) iron


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118.A primary cell and a secondary cell have the same emf .Which of

these will provide higher value of the maximum current that can be drawn?

a) primary cell b) secondary cell

d) both primary cell and secondary cell d) none of these119.A wire has a resistance of 10 ohm. If it is stretched by one tenth of

its original length , then its resistance will bea) 10 ohm b) 12.1 ohm c) 9 ohm d) 11 ohm

120.A wire has a resistance of 10 ohm. A second wire of the same

material having length double and radius of cross-section half that

of the first wire is there. The resistance of the second wire.

a) 20 ohm b) 40 ohm c) 80 ohm d) 10 ohm.

121.The resistance of a wire is R 1 ohm. The wire is stretched to doubleits length the resistance become R 2. Now, the ratio of R 1 and R 2 is

a) 1:1 b) 1:2 c) 1:4 d)4:1122.The resistance of a wire is R 1 ohm. The wire is stretched to double

its length the resistance become R 2. Now, the ratio of their resistivity

is

a) 1:1 b) 1:2 c) 1:4 d)4:1

123.Three resistances R 1 , R 2 and R 3 are connected in parallel. The

resultant resistance R isa) less than any of the three resistances

b) equal to sum of the three resistances

c) greater than the sum of the three resistances d) none of the above124.The specific resistance of the material of the wire depends on the

a) area of cross-section b) length c) mass d) none of the above125.Two unequal resistances are connected in parallel in a circuit .

Which one of the following statements is correct?

a) the current is same in both the resistances

b) the smaller resistance has the smaller conductancec)a large current flows through the larger resistance

d) the voltage drop across both the resistances is same

126.The difference of potential between the terminals of a cell in an

open circuit is called

a) emf b) resistance c) capacitance d) potential difference


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127.The difference of potential between the terminals of a cell in an

closed circuit is calleda) emf b) resistance c) capacitance d) potential difference

128. ‘ n’ similar resistors each of resistance ‘r’ when connected in

parallel has the total resistance R. When these resistances areconnected in series , the total resistance will be

a) n2R b) nR c) R/n d) R/n2 129.Ten identical resistances each having a resistance of 1 are joined

in parallel. Then combination has the resistance has the resistance of

a) 10 b) 1 c) 0.1 d) 0.01

130.In a Wheatstone bridge the resistances in the ratio arms are 100 and 150 respectively. If R=80 , the resistance of the fourth armwill be

a) 120 b) 80 c) 150 d) 70 131.A wire has resistance 12 ohm. It is bent in the form of a circle .The

effective resistance between the two points on any diameter of thecircle is

a) 12 b) 24 c) 6 d)3 132.In Wheatstone’s bridge ,P=9, Q=11 , R=4 and S= 6. How

much resistance must be put in parallel to the resistance S to

balance the bridge?

a) 24 b) 44/9 c) 26.4 d) 18.7 133.These are behaving like thermistor.

a) insulators and conductors b) semiconductors and conductors

c) conductors and alloys d) insulators and semiconductors134.When three resistors are connected in series then the value of the

effective resistance is

a) less than the individual resistance b) greater than the individual resistance

c)greater than or equal to individual resistanced)less than or equal to individual resistance

135.In the case of Wheatstone’s bridge , the bridge balance condition

will be obtained only when

a) the current through the galvanometer is maximum

b) the current through the galvanometer is minimum


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c) the current through the galvanometer is zero

d) the current through the galvanometer is infinity

136.If 0.2 is the resistance per unit length of the wire, then theresistance of the Metre bridge wire is

a) 2 b) 200 c) 0.2 d) 20 137.The mass of substance liberated during electrolysis is 0.6 g when 4A

of current flow for 2 minute. The chemical equivalent of thesubstance isa) 2.5x10

-6kg C

-1 b) 1.75x10

-6kg C

-1

c) 1.5x10-6

kg C-1

d) 1.25x10-6

kg C-1

138.The graph between voltage and current for ohmic conductors isa) curve b) straight line b) parabola d) ellipse

139.If a wire of resistivity is stretched to double its length , then itsnew resistivity will

a) be half b) be double c) be four times d) not change

140.As the temperature increases, resistivity of metals

a) remains constant b) decreases b)increases d) becomes zero141. As the temperature decreases, resistivity of materials

a) increases b) increases and decreases

c) decreases d) remains constant142.Which of the following is an identical pair?

a) germanium, silicon b) silver, wood

c) aluminium, constantan d) backelite, iron143.At the critical temperature the resistance of a superconductor

a) increases rapidly b) decreases rapidly

c) remains constant d) increases slowly

144.Abird sitting on an insulated wire carrying a current feels quite safe

because

a) the bird is a non-conductor of electricity

b) resistance of the bird is very large

c) there is a large potential difference between bird and wired) there is no potential difference between bird and wire

145.Resistivity and resistance of superconductors is

a) low, high b) zero, infinity c) zero , zero d)large , very large


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146.Which term is not connected with a Voltaic cell?

a) copper electrodes b) spongy leadc) zinc electrode d) dilute sulphuric acid

147.In primary cells electric energy is derived by

a) reversible chemical reactions b) isothermal processc) irreversible chemical reactions d) adiabatic process

148.The specific resistance of wire depends ona) its radius b) its length

c) the material of the wire d) the shape of the wire149.The resistance of a

a) thick conductor is less than that of a thin conductor

b) thin conductor is less than that of a thick conductorc) short conductor is more than that of a long conductor

d) both (a) and ( c)

150.The current flowing through a conductor is

a) directly proportional to drift velocity

b) inversely proportional to drift velocity

c) numerically equal to drift velocity

d) independent of drift velocity

151.If the radius of the conducting wire is doubled its resistivity

a) is doubled b) remains the samec) is halved d) is four time is initial value

152.The drift velocity acquired by unit electric field is called

a) conductivity b) resistitivity c) mobility d) conductance153.The drift velocity does not depend upon

a) magnetic field b) mass of the electron

c) charge of the electron d) relaxation time

154.Charging is the process of reproducing

a) current b) voltage c) power d) active material155.A wire of resistance R is divided into 10 equal parts. These parts are

connected in parallel, the equivalent resistance of such connection

will bea) 0.01R b) 0.1R c) 10R d) 100R

156.Wheatstone bridge is used to measure


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a) emf b) resistance c) current d) inductance

157.Manganin wire used in metre bridge and potentiometer has

a) zero resistivity b) high resisitivity

c) low temperature coefficient of resistance

d) high temperature of resistance

158.The length and area of cross section of a conductor are doubled

its resistance will bea) halved b) unchanged c) doubled d) increases four times

159.The direction of current and the direction of electrons are alwaysa) equal b) same c) opposite d) parallel

160.The net charge stored at any junction is equal to

a) zero b) maximum c)negative d)positive161.If a steady current is flowing through the potentiometer wire, then

the potential difference across any length is

a) directly proportional to square of the length b) inversely proportional to square of the length

c) inversely proportional to the length

d) directly proportional to the length

162.Thick copper strips, which is used in metre bridge have

a) low temperature coefficient b) high temperature coefficient

c) high resistance d) low resistance

163.The high resistance which is connected in the secondary circuit of a potentiometer allows

a) high current through the galvanometer

b) low current through the galvanometerc) zero current through the galvanometer

d) negative current

12th Physics Additional Questions (Vol 1)

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Transcript of 12th Physics Additional Questions (Vol 1)