Electrostatic Potential and Capacitance

An electric dipole is placed as shown in the figure. [figure] The electric potential (in 102 V) at point P due to the dipole is ( 0 = permittivity of free space and 14 0 = K) :

1. ( 58 ) qK
2. ( 85 ) qK
3. ( 83 ) qK
4. ( 38 ) qK

The angle between the electric lines of force and the equipotential surface is

1. 0
2. 45
3. 90
4. 180

Two hollow conducting spheres of radii R1 and R2 (R1 >> R2) have equal charges. The potential would be

1. More on bigger sphere
2. More on smaller sphere
3. Equal on both the spheres
4. Dependent on the material property of the sphere

A capacitor of capacitance C = 900 pF is charged fully by 100 V battery B as shown in figure (a). Then it is disconnected from the battery and connected to another uncharged capacitor of capacitance C = 900 pF as shown in figure (b). The electrostatic energy stored by the system (b) is [figure]

1. 4.5 10-6 J
2. 3.25 10-6 J
3. 2.25 10-6 J
4. 1.5 10-6 J

The distance between the two plates of a parallel plate capacitor is doubled and the area of each plate is halved. If C is its initial capacitance, its final capacitance is equal to

1. C4
2. 2C
3. C2
4. 4C

The effective capacitances of two capacitors are 3 and 16 , when they are connected in series and parallel respectively. The capacitance of two capacitors are :

1. 1.2 , 1.8
2. 10 , 6
3. 8 , 8
4. 12 , 4

Six charges +q, -q, +q, -q, +q, and -q are fixed at the corners of a hexagon of side d as shown in the figure. The work done in bringing a charge q0 to the centre of the hexagon from infinity is ( 0 - permittivity of free space) [figure]

1. -q24 0 d (6 - 1 2 )
2. Zero
3. -q24 0 d
4. -q24 0 d (3 - 1 2 )

A parallel plate capacitor has a uniform electric field E in the space between the plates. If the distance between the plates is 'd' and the area of each plate is 'A', the energy stored in the capacitor is : ( 0 = permittivity of free space)

1. E2Ad 0
2. 12 0E2
3. 0EAd
4. 12 0E2Ad

Polar molecules are the molecules :

1. having a permanent electric dipole moment
2. having zero dipole moment
3. acquire a dipole moment only in the presence of electric field due to displacement of charges
4. acquire a dipole moment only when magnetic field is absent

Two charged spherical conductors of radius R1 and R2 are connected by a wire. Then the ratio of surface charge densities of the spheres ( 1 / 2) is :

1. R12R22
2. R1R2
3. R2R1
4. ( R1R2 )