Electrostatic Potential and Capacitance

Figure below shows four plates each of area A and separated from one another by a distance d

What is the capacitance between P and Q ?

• $\frac{{\mathrm{\epsilon }}_0\mathrm{A}}{\mathrm{d}}$

• $\frac{2{\mathrm{\epsilon }}_0\mathrm{A}}{\mathrm{d}}$

• $\frac{3{\mathrm{\epsilon }}_0\mathrm{A}}{\mathrm{d}}$

• $\frac{4{\mathrm{\epsilon }}_0\mathrm{A}}{\mathrm{d}}$

A soap bubble is charged to a potential of 16 V. Its radius is, then doubled. The potential of the bubble now will be

• 16 V

• 8 V

• 4 V

• 2 V

4 point charges each +q is placed on the circumference of a circle of diameter 2d in such a way that they form a square. The potential at the centre is

• 0

• $\frac{4\mathrm{q}}{\mathrm{d}}$

• $\frac{4\mathrm{d}}{\mathrm{q}}$

• $\frac{\mathrm{q}}{4\mathrm{d}}$

64 identical spheres of charge q and capacitance C each are combined to form a large sphere. The charge and  capacitance of the large sphere is

• 64q, C

• 16q, 4C

• 64q, 4C

• 16q, 64C

If the charge on a capacitor is increased by 2 coulomb, the energy stored in it increases by 21 %. The original charge on the capacitor is

• 10 C

• 20 C

• 30 C

• 40 C

Four capacitors of equal capacitance have an equivalent capacitance C₁ when connected in series and an equivalent capacitance C₂ when connected in parallel. The ratio $\frac{{\mathrm{C}}_1}{{\mathrm{C}}_2}$ is

• 1/4

• 1/16

• 1/8

• 1/12

In the figure below, the capacitance of each capacitor is 3 µF. The effective capacitance between A and B is

• $\frac{3}{4} \mathrm{\mu F}$

• 3 µF

• 6 µF

• 5 µF

The charge on the capacitor of capacitance C shown in the figure below will be

• C E

• $\frac{\mathrm{C} \mathrm{E} {\mathrm{R}}_1}{{\mathrm{R}}_1 + \mathrm{r}}$

• $\frac{\mathrm{C}\hspace{0.17em}\mathrm{E}\hspace{0.17em}{\mathrm{R}}_2}{{\mathrm{R}}_2 + \mathrm{r}}$

• $\frac{\mathrm{C}\hspace{0.17em}\mathrm{E}\hspace{0.17em}{\mathrm{R}}_1}{{\mathrm{R}}_2 + \mathrm{r}}$

In the adjoining figure, the potential difference between X and Y is 60 V. The potential difference between the points M and N will be

• 10 V

• 15 V

• 20 V

• 30 V

A, B and C are three points in a uniform electric field. The electric potential is

• maximum at A

• maximum at B

• maximum at C

• same at all the three points A, B and C