Question No. 1

which of the following methods can be used to charge a metal sphere positively without touching it . Select the best

Connect the positive terminal a battery and float the other end of the battery

Bring a negatively charged rod near the sphere and touch it to ground for a short while

Rub it with a piece of silk 

Rub it with a piece of fur 

Clear

If {\rm{1}}{0^{\rm{9}}} electrons move out of a body to another body every second, how much time is approximately required to get a total charge of 1 C on the other body?

200 years 

120 years 

180 years

220 years

Electric charge

is a property of protons only

is a property of particles such as atoms,ions,electrons etc that defines their behaviour in electrical fields.

is a property of neutrons onlz

is a property of electrons only

Clear

Electric charges are of

4 types

2 types

5 types

3 types

Conservation of charges in tribo electric charging

implies both are negatively charged 

implies one is positively charged and the other is negatively charged.

implies half are positively charged and other half are neutral

implies both are positively charged

Clear

wo positive charges

always attract each other

repel each other

attract each other

attract each other at times and repel at other times

Clear

Charge is quantized means

charges can take on any continuous value

charges can take on discrete values that are multiples of charge on electron 

charges can take on discrete values that are multiples of charge on neutron

charges can take on any discontinuous value

Clear

Ionization of a neutral atom is the

only gain of one or more neutrons

only gain of one or more electrons

only gain of one or more protons

gain or loss of one or more electrons

electrostatic force is

force exerted by an electron on a neutron 

force exerted by one charge on another when the two are at rest in a given frame of reference

force exerted by one charge on another when the two are accelerating in a given frame of reference

force exerted by one charge on another when the two are moving in a given frame of reference

Clear

Conductors are materials

that allow only random movement of electrons

that allow movement of protons

that allow movement of electrons 

that allow movement of neutrons

Clear

In charging by Induction

a metallic object is charged by bringing a charged object near it

a metallic object by touching touching with a charged object 

a metallic object is charged by rubbing it with silk 

a metallic object is charged by rubbing it with fur

Clear

For charges q1andq2 separated by a distance R the magnitude of the electrostatic force is given by

B .  F=q1q24πϵ0R

F=q1q24πϵ0R3

F=q14πϵ0R2

F=q1q24πϵ0R2

.

The unit of charge is

ampere 

coulomb 

ohm

volt

Electric field at a point is defined as

electric force experienced by a dipole at that point

electric force per unit charge experienced by a unit charge at that point 

electric force experienced by a charge at that point

electric force experienced by two charges at that point

Clear

According to superposition of electric fields

The electric field of any combination of charges is the cross product of the individual fields.

The electric field of any combination of charges is the vector sum of the individual charges. 

The electric field of any combination of charges is the vector sum of the fields caused by the individual charges. 

The electric field of any combination of charges is the scalar sum of the fields caused by the individual charges.

Clear

Electric field lines can be said to be

lines of equal Electric field

graphical representation of electric fields.

drawing lines of electric fields 

lines of equal Electric voltage

Clear

At any point on S on an electric field line

the perpendicular to the line is in the direction of E ⃗  at that point

the curvature is in the direction of E ⃗  at that point

the tangent to the line is in the direction of E ⃗  at that point

the binormal to the line is in the direction of E ⃗ at that point 

Clear

An electric dipole is

a pair of electric charges of equal magnitude q but opposite sign, separated by a distance

a pair of electric charges of equal magnitude q but negative sign, separated by a distance d

a pair of electric charges of equal magnitude q but positive sign, separated by a distance d

a pair of electric charges of equal magnitude q separated by a distance d 

Clear

The direction of an electric dipole

is perpendicular to line from positive to negative charge

is from negative to positive charge

is perpendicular to line from negative to positive charge

is from positive to negative charge

Clear

Electric flux

Is a measure of the electric power through a surface

Is a measure of the electric field potential through a surface 

Is a measure of the area of electric field through a surface

Is a measure of the "flow" (in analogy with flow of fluids) of electric field through a surface.

Clear

Gauss's law states that

the total electric field flux coming out of a closed surface equals the net charge enclosed within the volume the total electric field flux coming out of a closed surface equals the net charge enclosed within the volume divided by ε0 the total electric field flux coming out of an open surface equals the net charge enclosed within the volume divided by ε0 the total electric field flux coming out of a closed surface equals the charge enclosed within the volume divided by ε0 

Clear

An electric dipole in an electric field experiences a torque {tex}\vec \tau {tex}

equal to the vector product of \vec E{tex} and {tex}\vec p  

equal to the scalar product of \vec p{tex}   and {tex}\vec E 

equal to the scalar product of {tex}\vec E{tex} and {tex}\vec p{tex}  

equal to the vector product of \vec p{tex}   and {tex}\vec E 

For a thin infinitely long straight wire of uniform linear charge density λ at a distance R from the wire

The magnitude of E ⃗  is

E=λ2πϵ0R.

E=λ22πϵ0R

B . E=λ4πϵ0R

E=λ3πϵ0R

For an Infinite thin plane sheet of uniform surface charge density σtexThemagnitudeof texE ⃗  is

A . E=σ2

ϵ0

E=σ22ϵ0

E=σ2ϵ03

E=σϵ0

For a thin spherical shell of uniform surface charge density σ , The magnitude of E ⃗  just outside is

E=4πRσ24πϵ0

r2

E=4πR2σ4πϵ0

r3

A . E=R2σ4πϵ0r2

E=4πR2σ4πϵ0

r2

Clear

An electric field can deflect

γ - rays

X rays

α – rays

Neutrons

Clear

Which one of the following graphs represents the variation of electric field strength E with distance ‘r’ from the centre of a uniformly charged non conducting sphere?

Image B

Image C

Image D

Image A

Clear

A conducting sphere of radius 5 cm is charged to 15 {tex}\mu {tex} C. Another uncharged sphere of radius 10 cm is allowed to touch it for enough time. After the two are separated, the surface density of charge on the two spheres will be in the ratio

0.0840277777778

0.0423611111111

0.125694444444

0.0430555555556

Clear

A Gaussian sphere encloses an electric dipole within it. Total flux across the sphere is

dependent on position of the charge

double that due to single charge

half that due to a single charge

Zero

A cylinder of radius R and length L is placed in an uniform electric field E parallel to the cylinder axis. The total flux for the surface of the cylinder is given by

πR2E

2πR2EπR2+πL2C .0

When a negatively charged conductor is connected to earth,

Electrons flow from the conductor to the earth

Protons flow from the conductor to the earth

Electrons flow from the earth to the conductor

An uncharged sphere of metal is placed inside a charged parallel plate capacitor. The lines of force look like

Correct option is B

Correct option is A

Correct option is C 

Correct option is D

Clear

Answer Sheet

General

1 2 3 45 6 7 89 101112131415Submit Test

Previous

A hollow spherical conductor of radius 2m carries a charge of 500 μ C. Then electric field strength at its surface is

1.125×106N/C .

4.5×106N/C2.25×106N/CZero

Clear

A tennis ball which has been covered with charges is suspended by a thread so that it hangs between two metal plates. One plate is earthed, while other is attracted to a high voltage generator. The ball

hangs without moving

is attracted to the high voltage plate and stays there

swings backward & forward hitting each plate in turn

is repelled by earthed plate and stays there.

Clear

A metallic solid sphere is placed in a uniform electric field. In the figure, which path will the lines of

force follow?

3.0

1.0

4.0

2.0

Eight dipoles of charges of magnitude e are placed inside a cube. The total electric flux coming out of the cube will be

16eϵo

A .8eϵo

eϵo

Zero

A charge q is placed at the center of the line joining two equal charges Q. The system of the three charges will be in equilibrium if q is equal to

Q/2

Q/4

Q/5

Q/2

Four point charges qA=2μC,qB=−5μC,qC=2μC,andqD=−5μC are located at the corners of a square ABCD of side 10 cm. Force on a charge of 1μC placed at the centre of the square is

1.8 N

4.5 N

3.6

0 N

A system has two charges qA=2.5×10−7C and qB=−2.5×10−7C located at points A: (0, 0, –15 cm) and B: (0,0, +15 cm), respectively. What are the total charge and electric dipole moment of the system?

zero, 7.5×10−8

Cmzero, 6.5×10−8

Cmzero, 5.5×10−8

Cmzero, 8.5×10−8

CmAn electric dipole with dipole moment 4×10−9C m is aligned at 30∘ with the direction of a uniform electric field of magnitude 5×104NC−1. Calculate the magnitude of the torque acting on the dipole.

3.5×10−4

Cm1.0×10−4

Cm1.5×10−8

Nm2.5×10−4

CmTwo insulated charged copper spheres A and B have their centres separated by a distance of 50 cm. What is the mutual force of electrostatic repulsion if the charge on each is 6.5×10−7C? The radii of A and B are negligible compared to the distance of separation.

B 2.5×10−2N

3.5×10−2

N

1.5×10−2

N

4.5×10−2

N

Clear

Two insulated charged copper spheres A and B have their centres separated by a distance of 50 cm and have identical sizes. A third sphere of the same size but uncharged is brought in contact with the first, then brought in contact with the second, and finally removed from both. What is the new force of repulsion between A and B?

A 3.7×10−

3/N6.7×10−3/N5.7×10−3/N4.7×10−3/N

Consider a uniform electric field E=3×103N/C. (a) What is the flux of this field through a square of 10

cm on a side whose plane is parallel to the yz plane? (b) What is the flux through the same square if the normal to its plane makes a 60∘ angle with the x-axis?

40Nm2/C,25Nm2/C

40Nm2/C,15Nm2/C

30Nm2/C,15Nm2/C

A 20Nm2/C,15Nm2/C

Clear

Careful measurement of the electric field at the surface of a black box indicates that the net outward

flux through the surface of the box is 8.0×103Nm2/C. (a) What is the net charge inside the box? (b)

If the net outward flux through the surface of the box were zero, could you conclude that there were no charges inside the box?

0.05 μC, No

0.07 μC, No

0.06 μC, Yes

A 0.04 μC, Yes

A point charge of 2.0 μC is at the centre of a cubic Gaussian surface 9.0 cm on edge. What is the net electric flux through the surface?

2.2×105Nm2

/C

2.1×105Nm2

/C

A 1.7×105Nm2/C

1.9×105Nm2

/C

Clear

 point charge causes an electric flux of −1.0×103Nm2/C to pass through a spherical Gaussian surface of 10.0 cm radius centred on the charge. (a) If the radius of the Gaussian surface were doubled, how much flux would pass through the surface? (b) What is the value of the point charge?

B 103Nm2/C,−8.8nC

−103Nm2/C,−6.8nC

103Nm2/C,−7.8nC

−103Nm2/C,−8.8nC

A point charge + q is placed at the mid point of a cube of side L. The electric flux emerging from the cube is

qϵo

zeroq6L2ϵoqL2ϵo

A uniformly charged conducting sphere of 2.4 m diameter has a surface charge density of 80.0μC/m2. (a) Find the charge on the sphere. (b) What is the total electric flux leaving the surface of the sphere?

1.35×10−3C,1.6×108Nm2/C

1.45×10−3C,1.6×108Nm2/C

1.55×10−3C,1.6×108Nm2/C

A 1.25×10−3C,1.2×108

Nm2/C

Clear

Gravitational force is the smallest between

two pens weighing 100gms at a distance of 0.4 m

earth and the sun

earth and the sun

two books of weight 1kg each at a distance of 1 m

Clear

A solid metallic sphere has a charge + 3Q. Concentric with this sphere is a conducting spherical

shell having charge –Q. The radius of the sphere is ‘a’ and that of spherical shell is ‘b’ (b>a). The

electric field at a distance R (a<r)

A . 4Q4πε0R2

3Q4πε0R

3Q4πε0R2

Q4πε0R

Six charges, each equal to + q, are placed at the corners of a regular hexagon of side a. The electric field at the point of intersection of diagonals is

Zero

14πϵo.6qa2

14πϵo.3q√2a2

14πϵo.qa2

A pendulum bob of mass m carrying a charge q is at rest with its string making an angle θ with the vertical in a uniform horizontal electric field E. The tension in the string is

qEcosθ

mgmgsinθqEsinθ

A particle of mass m and charge q is released from rest in a uniform electric field E. The kinetic energy attained by the particle after moving a distance x is

qE2

xqEx2

q2Ex

qEx

There is a uniform field of strength 103Vm−1 along the y-axis. A body of mass 1 g and

charge 10−−6C is projected into the field from the origin along the positive x-axis with a velocity

of 10ms−1. Its speed (in ms−1 after 10 second will be (neglect gravitation)

10.0

20.0

102√

52√

A uniformly charged thin spherical shell of radius R carries uniform surface charge density of {tex}\

sigma {tex} per unit area. It is made of two hemispherical shells, held together by pressing them with

force F(See figure). F is proportional to 

σ2R2ϵ0

1ϵ0σ2

R1ϵ0σ2

R2

σ2Rϵ0

Two charges A = -2.50 μC and B = 6.0 μC are at a distance of 1 meter from each other. Distance from A at which the electric field is zero in meters is

2.22

1.92

1.82

2.03

A long, hollow conducting cylinder is kept coaxially inside another long, hollow conducting cylinder of larger radius. Both the cylinders are initially electrically neutral.

A potential difference appears between the two cylinders when a charge density is given to the inner cylinder.

No potential difference appears between the two cylinders when a uniform line charge is kept along the axis of the cylinders.

A potential difference appears between the two cylinders when a charge density is given to the outer cylinder.

No potential difference appears between the two cylinders when same charge density is given to both the cylinders.

Clear

Consider a neutral conducting sphere. A positive point charge is placed outside the sphere. The net charge on the sphere is then,

Zero.

Negative and distributed non–uniformly over the entire surface of the sphere

Negative and appears only at the point on the sphere closest to the point charge

Negative and distributed uniformly over the surface of the sphere.

Clear

Two equal positive charges q1 = q2 = 2.0 μC are located at x = 0, y =0.3 and x =0 and y = -0.3 m

respectively. What are the magnitude and direction of the total electric force (expressed in Newton and degrees counter clockwise w.r.t x - axis) that q1 and q2 exert on a third charge Q = 4.0 μC at x =0.4 and y = 0 m

0.46,0.00

0.48,3.00

0.44,2.00

0.42,1.00

Positive and negative point charges of equal magnitude are kept at ( 0,0,a/2) and (0,0,-a/2)

respectively. The work done by the electric field when another positive point charge is moved from (-a,0,0) to (0,a,0) is

depends on the path connecting the initial and final positions

positive

negative

Zero

Clear

A disk of radius a/4 having a uniformly distributed charge 6C is placed in the x-y plane with its

centre at (−a/2, 0, 0). A rod of length a carrying a uniformly distributed charge 8C is placed on the x-

axis from x = a/4 to x = 5a/4. Two point charges −7C and 3C are placed at (a/4, −a/4, 0) and (−3a/4,

3a/4, 0), respectively. Consider a cubical surface formed by six surfaces x=±a/2,y=±a/2,z=±a/2. The

electric flux through this cubical surface is 

−2Cϵ0

B . 2Cϵ0

12Cϵ0

10Cϵ0

Three concentric metallic spherical shells of radii R, 2R, 3R, are given charges Q1, Q2, Q3, respectively. It is found that the surface charge densities on the outer surfaces of the shells are equal. Then, the ratio of the charges given to the shells, Q1: Q2: Q3, is

it is 1:08:18

it is 1:04:09

it is 1:02:03

it is 1:03:05

Three concentric metallic spherical shells of radii R, 2R, 3R, are given charges Q1, Q2, Q3, respectively. It is found that the surface charge densities on the outer surfaces of the shells are equal. Then, the ratio of the charges given to the shells, Q1: Q2: Q3, is

it is 1:08:18

it is 1:04:09

it is 1:02:03

it is 1:03:05