Electrostatic Potential and Capacitance

In this diagram, the PD between A and B is 60 V. The PD across 6 µF capacitor is

• 4 V

• 10 V

• 5 V

• 20 V

A capacitor of capacitance 10 µF is charged to 10 V. The energy stored in it is

• 1 µJ

• 100 µJ

• 500 µJ

• 1000 µJ

Which of the following graphs correctly represents the variation of heat energy (U) produced in a metallic conductor in a given time as a function of potential difference (V) across the conductor ?

The concentric spheres of radii R and r have positive charges q₁ and q₂ with equal surface charge densities. What is the electric potential at their common centre ?

• $\frac{\mathrm{\sigma }}{{\mathrm{\epsilon }}_0} \left(\mathrm{R} + \mathrm{r}\right)$

• $\frac{\mathrm{\sigma }}{{\mathrm{\epsilon }}_0} \left(\mathrm{R} - \mathrm{r}\right)$

• $\frac{\mathrm{\sigma }}{{\mathrm{\epsilon }}_0} \left(\frac{1}{\mathrm{R}} + \frac{1}{\mathrm{r}}\right)$

• $\frac{\mathrm{\sigma }}{{\mathrm{\epsilon }}_0} \left(\frac{1}{\mathrm{R}}\right)$

When an additional charge of 2C is given to a capacitor, energy stored in it is increased by 21%. The original charge of the capacitor is

• 30 C

• 40 C

• 10 C

• 20 C

When a potential difference of 10³ V is applied between A and B, a charge of 0. 75 mC is value of C is (in μF)

• $\frac{1}{2}$

• 2

• 2.5

• 3

See the diagram. Area of each plate is 2.0 m² and d = 2 x 10^-3 m. A charge of 8.85 x 10^-8 C is given to Q. Then the potential of Q becomes

• 13 V

• 10 V

• 6.67 V

• 8.825 V

What is the electric potential at a distance of 9 cm from 3 nC ?

• 270 V

• 3 V

• 300 V

• 30 V

A voltmeter reads 4 V when connected to a parallel plate capacitor with air as a dielectric. When a dielectric slab is introduced between plates for the same configuration, voltmeter reads 2 V. What is the dielectric constant of the material ?

• 0.5

• 2

• 8

• 10

Two capacitors of 10 pF and 20 pF are connected to 200 V and 100 V sources respectively. If they are connected by the wire, what is the common potential of the capacitors ?

• 133.3 V

• 150 V

• 300 V

• 400 V