# Electrostatics Test 6

Total Questions:50 Total Time: 75 Min

Remaining:

## Questions 1 of 50

Question:Out of gravitational, electromagnetic, Vander Waals, electrostatic and nuclear forces; which two are able to provide an attractive force between two neutrons

Electrostatic and gravitational

Electrostatic and nuclear

Gravitational and nuclear

Some other forces like Vander Waals

## Questions 2 of 50

Question:A total charge Q is broken in two parts $${Q_1}$$ and $${Q_2}$$ and they are placed at a distance $$R$$ from each other. The maximum force of repulsion between them will occur, when

$${Q_2} = \frac{Q}{R},\;{Q_1} = Q - \frac{Q}{R}$$

$${Q_2} = \frac{Q}{4},\;{Q_1} = Q - \frac{{2Q}}{3}$$

$${Q_2} = \frac{Q}{4},\;{Q_1} = \frac{{3Q}}{4}$$

$${Q_1} = \frac{Q}{2},\;{Q_2} = \frac{Q}{2}$$

## Questions 3 of 50

Question:A force $$F$$ acts between sodium and chlorine ions of salt (sodium chloride) when put $$1\,cm$$ apart in air. The permittivity of air and dielectric constant of water are $${\varepsilon _0}$$ and $$K$$ respectively. When a piece of salt is put in water electrical force acting between sodium and chlorine ions $$1\,cm$$ apart is

$$\frac{F}{K}$$

$$\frac{{FK}}{{{\varepsilon _0}}}$$

$$\frac{F}{{K{\varepsilon _0}}}$$

$$\frac{{F{\varepsilon _0}}}{K}$$

## Questions 4 of 50

Question:A conductor has $$14.4 \times {10^{ - 19}}coulombs$$ positive charge. The conductor has (Charge on electron $$= 1.6 \times {10^{ - 19}}coulombs$$ )

9 electrons in excess

27 electrons in short

27 electrons in excess

9 electrons in short

## Questions 5 of 50

Question:Two charges each equal to $$2\mu C$$ are 0.5m apart. If both of them exist inside vacuum, then the force between them is

1.89 N

2.44 N

0.144 N

3.144 N

## Questions 6 of 50

Question:Two charges are at a distance 'd' apart. If a copper plate (conducting medium) of thickness $$\frac{d}{2}$$ is placed between them, the effective force will be

2F

F / 2

0

$$\sqrt 2 F$$

## Questions 7 of 50

Question:Two spherical conductors B and C having equal radii and carrying equal charges in them repel each other with a force F when kept apart at some distance. A third spherical conductor having same radius as that of B but uncharged is brought in contact with B, then brought in contact with C and finally removed away from both. The new force of repulsion between B and C is

$$F/4$$

$$3F/4$$

$$F/8$$

$$3F/8$$

## Questions 8 of 50

Question:When a body is earth connected, electrons from the earth flow into the body. This means the body is.

Unchanged

Charged positively

Charged negatively

An insulator

## Questions 9 of 50

Question:The electric field inside a spherical shell of uniform surface charge density is

Zero

Constant, less than zero

Directly proportional to the distance from the centre

None of the above

## Questions 10 of 50

Question:The electric potential $$V$$ at any point O (x, y, z all in metres) in space is given by $$V = 4{x^2}\,volt$$. The electric field at the point $$(1m,\,0,\,2m)$$ in $$volt/metre$$ is

8 along negative $$X -$$axis

8 along positive $$X -$$axis

16 along negative $$X -$$axis

16 along positive $$Z -$$axis

## Questions 11 of 50

Question:If $$E$$ is the electric field intensity of an electrostatic field, then the electrostatic energy density is proportional to

$$E$$

$${E^2}$$

$$1/{E^2}$$

$${E^3}$$

## Questions 12 of 50

Question:A metallic sphere has a charge of $$10\mu C$$. A unit negative charge is brought from $$A$$to $$B$$ both $$100\,cm$$ away from the sphere but A being east of it while $$B$$being on west. The net work done is

Zero

$$2/10\;joule$$

$$- 2/10\;joule$$

$$- 1/10\;joule$$

## Questions 13 of 50

Question:Angle between equipotential surface and lines of force is

Zero

$$180^\circ$$

$$90^\circ$$

$$45^\circ$$

## Questions 14 of 50

Question:The unit of electric field is not equivalent to

$$N/C$$

$$J/C$$

$$V/m$$

$$J/C - m$$

## Questions 15 of 50

Question:Two point charges $$100\,\mu \,C$$ and $$5\,\mu \,C$$ are placed at points $$A$$ and $$B$$ respectively with $$AB = 40\,cm$$. The work done by external force in displacing the charge $$5\,\mu \,C$$ from $$B$$ to $$C$$, where $$BC = 30\,cm$$, angle $$ABC = \frac{\pi }{2}$$ and $$\frac{1}{{4\pi {\varepsilon _0}}} = 9 \times {10^9}N{m^2}/{C^2}$$

$$9\,J$$

$$\frac{{81}}{{20}}J$$

$$\frac{9}{{25}}J$$

$$- \frac{9}{4}J$$

## Questions 16 of 50

Question:The unit of intensity of electric field is

$$Newton/Coulomb$$

$$Joule/Coulomb$$

$$Volt - metre$$

$$Newton/metre$$

## Questions 17 of 50

Question:How much kinetic energy will be gained by an $$\alpha -$$particle in going from a point at $$70\,V$$ to another point at $$50\,V$$

$$40\,eV$$

$$40\,keV$$

$$40MeV$$

$$0\,eV$$

## Questions 18 of 50

Question:If a charged spherical conductor of radius $$10\,cm$$has potential $$V$$ at a point distant $$5\,cm$$ from its centre, then the potential at a point distant $$15\,cm$$ from the centre will be

$$\frac{1}{3}V$$

$$\frac{2}{3}V$$

$$\frac{3}{2}V$$

$$3V$$

## Questions 19 of 50

Question:Two positive point charges of $$12\mu C$$ and $$8\mu C$$ are 10cm apart. The work done in bringing them 4 cm closer is

5.8 J

5.8 eV

13 J

13 eV

## Questions 20 of 50

Question:The displacement of a charge Q in the electric field $$E = {e_1}\hat i + {e_2}\hat j + {e_3}\hat k$$ is $$\hat r = a\hat i + b\hat j$$. The work done is

$$Q(a{e_1} + b{e_2})$$

$$Q\sqrt {{{(a{e_1})}^2} + {{(b{e_2})}^2}}$$

$$Q({e_1} + {e_2})\sqrt {{a^2} + {b^2}}$$

$$Q(\sqrt {e_1^2 + e_2^2)} \;(a + b)$$

## Questions 21 of 50

Question:A hollow conducting sphere of radius $$R$$ has a charge $$( + Q)$$ on its surface. What is the electric potential within the sphere at a distance $$r = \frac{R}{3}$$ from its centre

Zero

$$\frac{1}{{4\pi {\varepsilon _0}}}\frac{Q}{r}$$

$$\frac{1}{{4\pi {\varepsilon _0}}}\frac{Q}{R}$$

$$\frac{1}{{4\pi {\varepsilon _0}}}\frac{Q}{{{r^2}}}$$

## Questions 22 of 50

Question:Kinetic energy of an electron accelerated in a potential difference of 100 V is

$$1.6 \times {10^{ - 17}}$$J

$$1.6 \times {10^{21}}$$J

$$1.6 \times {10^{ - 29}}$$J

$$1.6 \times {10^{ - 34}}$$J

## Questions 23 of 50

Question:An electron moving with the speed $$5 \times {10^6}$$ per sec is shooted parallel to the electric field of intensity $$1 \times {10^3}N/C$$. Field is responsible for the retardation of motion of electron. Now evaluate the distance travelled by the electron before coming to rest for an instant (mass of $$e = 9 \times {10^{ - 31}}Kg.$$ charge $$= 1.6 \times {10^{ - 19}}C)$$

7 m

0.7 mm

7 cm

0.7 cm

## Questions 24 of 50

Question:A hollow metal sphere of radius 5cm is charged such that the potential on its surface is 10V. The potential at a distance of 2cm from the centre of the sphere

Zero

10 V

4 V

10/3 V

## Questions 25 of 50

Question:Point charge $${q_1} = 2\mu C$$ and $${q_2} = - 1\,\mu C$$ are kept at points $$x = 0$$ and $$x = 6$$ respectively. Electrical potential will be zero at points

$$x = 2$$ and $$x = 9$$

$$x = 1$$ and $$x = 5$$

$$x = 4$$ and $$x = 12$$

$$x = - 2$$ and $$x = 2$$

## Questions 26 of 50

Question:A hollow metallic sphere of radius R is given a charge Q. Then the potential at the centre is

Zero

$$\frac{1}{{4\pi {\varepsilon _0}}}.\frac{Q}{R}$$

$$\frac{1}{{4\pi {\varepsilon _0}}}.\frac{{2Q}}{R}$$

$$\frac{1}{{4\pi {\varepsilon _0}}}.\frac{Q}{{2R}}$$

## Questions 27 of 50

Question:The electric field at a point on equatorial line of a dipole and direction of the dipole moment

Will be parallel

Will be in opposite direction

Will be perpendicular

Are not related

## Questions 28 of 50

Question:A molecule with a dipole moment p is placed in an electric field of strength E. Initially the dipole is aligned parallel to the field. If the dipole is to be rotated to be anti-parallel to the field, the work required to be done by an external agency is

2pE

pE

pE

2pE

## Questions 29 of 50

Question:A charge $$q$$ is placed at the centre of the open end of cylindrical vessel. The flux of the electric field through the surface of the vessel is

Zero

$$\frac{q}{{{\varepsilon _0}}}$$

$$\frac{q}{{2{\varepsilon _0}}}$$

$$\frac{{2q}}{{{\varepsilon _0}}}$$

## Questions 30 of 50

Question:A capacitor is charged by using a battery which is then disconnected. A dielectric slab is then slipped between the plates, which results in

Reduction of charge on the plates and increase of potential difference across the plates

Increase in the potential difference across the plate, reduction in stored energy, but no change in the charge on the plates

Decrease in the potential difference across the plates, reduction in the stored energy, but no change in the charge on the plates

None of the above

## Questions 31 of 50

Question:No current flows between two charged bodies connected together when they have the same

Capacitance or $$\frac{Q}{V}$$ ratio

Charge

Resistance

Potential or $$\frac{Q}{C}$$ratio

## Questions 32 of 50

Question:The radii of two metallic spheres $$P$$ and $$Q$$ are $${r_1}$$ and$${r_2}$$ respectively. They are given the same charge. If $${r_1} > {r_2}$$. then on connecting them with a thin wire, the charge will flow

From P to Q

From Q to P

Neither the charge will flow from P to Q nor from Q to P

The information is incomplete

## Questions 33 of 50

Question:The outer sphere of a spherical air capacitor is earthed. For increasing its capacitance

Vacuum is created between two spheres

Dielectric material is filled between the two spheres

The space between two spheres is increased

The earthing of the outer sphere is removed

## Questions 34 of 50

Question:A capacitor is kept connected to the battery and a dielectric slab is inserted between the plates. During this process

No work is done

Work is done at the cost of the energy already stored in the capacitor before the slab is inserted

Work is done at the cost of the battery

Work is done at the cost of both the capacitor and the battery

## Questions 35 of 50

Question:A parallel plate capacitor is first charged and then a dielectric slab is introduced between the plates. The quantity that remains unchanged is

Charge $$Q$$

Potential $$V$$

Capacity $$C$$

Energy $$U$$

## Questions 36 of 50

Question:A $$10\,pF$$ capacitor is connected to a 50 V battery. How much electrostatic energy is stored in the capacitor

$$1.25 \times {10^{ - 8}}\,J$$

$$2.5 \times {10^{ - 7}}\,J$$

$$3.5 \times {10^{ - 5}}\,J$$

$$4.5 \times {10^{ - 2}}\,J$$

## Questions 37 of 50

Question:While a capacitor remains connected to a battery and dielectric slab is applied between the plates, then

Potential difference between the plates is changed

Charge flows from the battery to the capacitor

Electric field between the plates increases

Energy store in the capacitor decreases

## Questions 38 of 50

Question:If there are n capacitors in parallel connected to V volt source, then the energy stored is equal to

CV

$$\frac{1}{2}nC{V^2}$$

$$C{V^2}$$

$$\frac{1}{{2n}}C{V^2}$$

## Questions 39 of 50

Question:A parallel plate capacitor of capacity $${C_0}$$ is charged to a potential $${V_0}$$ (i) The energy stored in the capacitor when the battery is disconnected and the separation is doubled $${E_1}$$ (ii) The energy stored in the capacitor when the charging battery is kept connected and the separation between the capacitor plates is doubled is $${E_2}.$$ Then $${E_1}/{E_2}$$ value is

4

3/2

2

1/2

## Questions 40 of 50

Question:If the distance between the plates of parallel plate capacitor is halved and the dielectric constant of dielectric is doubled, then its capacity will

Increase by 16 times

Increase by 4 times

Increase by 2 times

Remain the same

## Questions 41 of 50

Question:Three capacitors of capacity $${C_1},\;{C_2}\;{C_3}$$ are connected in series. Their total capacity will be

$${C_1} + {C_2} + {C_3}$$

$$1/({C_1} + {C_2} + {C_3})$$

$${(C_1^{ - 1} + C_2^{ - 1} + C_3^{ - 1})^{ - 1}}$$

None of these

## Questions 42 of 50

Question:Minimum number of capacitors of $$2\mu F$$ capacitance each required to obtain a capacitor of $$5\mu F$$ will be

Three

Four

Five

Six

## Questions 43 of 50

Question:A condenser of capacitance $$10\mu F$$ has been charged to 100$$volts$$. It is now connected to another uncharged condenser in parallel. The common potential becomes 40$$volts$$. The capacitance of another condenser is

$$15\mu F$$

$$5\mu F$$

$$10\mu F$$

$$16.6\mu F$$

## Questions 44 of 50

Question:A potential difference of 300 volts is applied to a combination of 2.0$$\mu$$F and 8.0$$\mu$$F capacitors connected in series. The charge on the 2.0$$\mu$$F capacitor is

$$2.4 \times {10^{ - 4}}$$C

$$4.8 \times {10^{ - 4}}$$C

$$7.2 \times {10^{ - 4}}$$C

$$9.6 \times {10^{ - 4}}$$C

## Questions 45 of 50

Question:Ten capacitor are joined in parallel and charged with a battery up to a potential V. They are then disconnected from battery and joined again in series then the potential of this combination will be

V

10V

5V

2V

## Questions 46 of 50

Question:Two capacitors of capacitance 2$$\mu$$F and $$3\mu F$$ are joined in series. Outer plate first capacitor is at 1000 volt and outer plate of second capacitor is earthed (grounded). Now the potential on inner plate of each capacitor will be

700 Volt

200 Volt

600 Volt

400 Volt

## Questions 47 of 50

Question:Three capacitors 2, 3 and 6 $$\mu$$F are joined in series with each other. What is the minimum effective capacitance

$$\frac{1}{2}\mu F$$

$$1\mu F$$

$$2\mu F$$

$$3\mu F$$

## Questions 48 of 50

Question:In the figure below, what is the potential difference between the point A and B and between B and C respectively in steady state

$${V_{AB}} = {V_{BC}} = 100\,V$$

$${V_{AB}} = 75\,V,\;{V_{BC}} = 25\;V$$

$${V_{AB}} = 25\,V,\;{V_{BC}} = 75\;V$$

$${V_{AB}} = {V_{BC}} = 50\;V$$

## Questions 49 of 50

Question:The electric field due to a uniformly charged sphere of radius R as a function of the distance from its centre is represented graphically by

## Questions 50 of 50

Question:What physical quantities may $$X$$ and $$Y$$ represent ? ($$Y$$ represents the first mentioned quantity)