CBSE Class 12th Physics Chapter 2 - Electrostatic Potential and Capacitance Important Questions with Answers

(i) Find equivalent capacitance between A and B in the combination given below. Each capacitor is of 2 µF capacitance

(ii) If a dc source of 7 V is connected across AB, how much charge is drawn from the source and what is the energy stored in the network? (Delhi 2015)

Two identical capacitors of 12 pF each are connected in series across a battery of 50 V. How much electrostatic energy is stored in the combination ? If these were connected in parallel across the same battery, how much energy will be stored in the combination now? Also find the charge drawn from the battery in each case. (Delhi 2015)

(a) Write two properties by which electric potential is related to the electric field.
(b) Two point charges q₁ and q₂, separated by a distance of r₁₂ are kept in an external electric field. Derive an expression for the potential energy of the system of two charges in the field. (Comptt. Delhi 2015)

A capacitor of unknown connected across a battery of V volt. A charge of 360 pC is stored in it. When the potential across the capacitor is reduced by 120 V, the charge stored in the capacitor becomes 120 pC. Calculate V and the unknown capacitance. What would have been the charge on the capacitor if the voltage were increased by 120 V? (Comptt. Delhi 2015)

A capacitor of unknown capacitance is connected across a battery of V volt. A charge of 240 pC is stored in it. When the potential across the capacitor is reduced by 80 V, the charge stored in the capacitor becomes 80 pC. Calculate V and the unknown capacitance. What would have been the charge in the capacitor if the voltage were increased by 80 V? (Comptt. Delhi 2015)

A capacitor of unknown capacitance is connected across a battery of V volt. A charge of 120 ?C is stored in it. When the potential across the capacitor is reduced by 40 V, the charge stored in the capacitor becomes 40 ?C. Calculate V and the unknown capacitance. What would have been the charge in the capacitor if the voltage were increased by 40 V? (Comptt. Delhi 2015)

A parallel plate capacitor of capacitance C is charged to a potential V by a battery. Without disconnecting the battery, the distance between the plates is tripled and a dielectric medium of k = 10 is introduced between the plates is tripled and a dielectric medium of k = 10 is introduced between the plates of the capacitor. Explain giving reasons, how will the following be affected:
(i) capacitance of the capacitor
(ii) charge on the capacitor, and
(iii) energy density of the capacitor. (Comptt. Outside Delhi 2015)

Derive the expression for the electric potential at any point P, at distance r from the centre of an electric dipole, making angle a, with its axes. (Comptt. All India 2015)

(a) Explain, using suitable diagrams, the difference in the behaviour of a
(i) conductor and
(ii) dielectric in the presence of external electric field. Define the terms polarization of a dielectric and write its relation with susceptibility.
(b) A thin metallic spherical shell of radius R carries a charge Q on its surface. A point charge \(\frac{Q}{2}\) is placed at its centre C and another charge +2Q is placed outside the shell at a distance x from the centre as shown in the figure.

Find
(i) the force on the charge at the centre of shell and at the point A,
(ii) the electric flux through the shell. (Delhi 2015)

“For any charge configuration, equipotential surface through a point is normal to the electric field.” Justify. (Delhi 2014)