221.

Across each of two capacitors of capacitance 1F, a potential difference of 10 V is applied. Then the positive plate of one is connected to the negative plate of the other, and the negative plate of one is connected to the positive plate of the other. After contact :

• charge on each is zero

• charge on each is same but non zero

• charge on each is different but non zero

A solid metal sphere of radius 50 cm carries a charge 25 x 10^-10 C, The electrostatic potential at a distance of 20 cm from the centre will be :

• 25 V

• 15 V

• 35 V

• 45 V

Two plates (area = S) charged to + q₁ and + q₂ (q₂ <q₁)are brought closer to form a capacitor of capacitance C. The potential difference across the plates is :

• $\frac{\mathrm{q}1 - \mathrm{q}2}{2\mathrm{C}}$

• $\frac{{\mathrm{q}}_1 - {\mathrm{q}}_2}{\mathrm{C}}$

• $\frac{{\mathrm{q}}_1 - {\mathrm{q}}_2}{4\mathrm{C}}$

• $\frac{2({\mathrm{q}}_1 - {\mathrm{q}}_2)}{\mathrm{C}}$

The capacity of an isolated conducting sphere of radius R is proportional to :

• R²

• 1/R²

• 1/R

• R

If a positive charge is shifted from a low potential region to a high potential region, the electric potential energy :

• decreases

• increases

• remains the same

• may increase or decrease

n small metal drops of same size are charged to V volt each. If they coalesce to form a single large drop, then its potential will be:

• $\frac{\mathrm{V}}{\mathrm{n}}$

• Vn

• ${\mathrm{Vn}}^{\frac{1}{3}}$

• ${\mathrm{Vn}}^{\frac{2}{3}}$

A parallel plate air capacitor is charged and then isolated. When a dielectric material is inserted between the plates of the capacitor, then which of the following does not change?

• Electric field between the plates

• Potential difference across the plates

• Charge on the plates

• Energy stored in the capacitor

A spherical drop of mercury having a potential of 2.5 V is obtained as a result of merging 125 droplets. The potential of a constituent droplet would be

• 1.0 V

• 0.5 V

• 0.2 V

• 0.1 V

A capacitor is connected to a cell of emf E having some internal resistance r, The potential difference across the :

• cell is < E

• cell is E

• capacitor is > E

• capacitor is < E

A capacitor of capacitance 6 µF is charged upto 100 volts. The energy stored in the capacitor is :

• 0.6 joule

• 0.06 joule

• 0.03 joule

• 0.3 joule