PART-A Questions carrying ONE mark each

1. How is electrical potential due to a point charge related to the distance at a point?
2. What is the total work done in moving a unit positive charge from one point to another on an equipotential surface?
3. What is an equipotential surface?
4. What is meant by dielectric strength?
5. What is electrostatic shielding?
6. How does a capacitance of a parallel plate capacitor change when the area of its plates is doubled?
7. Mention the use of Van de Graff generator.

PART-B Questions carrying TWO marks each

1. Write any two properties of an equipotential surface.
2. What is electrostatic shielding? Mention one application of electrostatic shielding.
3. Write the expression for potential energy of an electric dipole placed in a uniform electric field and explain the terms used.
4. Mention any two factors on which the capacitance of a parallel plate capacitor depends.
5. Draw a labelled diagram of Van de Graff generator.
6. Distinguish between polar molecules and non polar molecules.

PART C Questions carrying THREE marks each

1. Derive the expression for potential energy of a system of two charges in the absence of the external electric field.
2. Derive the expression for capacitance of a parallel plate capacitor.
3. Derive the relationship between electric field and electric potential
4. Derive an expression for the potential energy of an electric dipole in a uniform electric field.
5. Derive an expression foe potential energy stored in the system of three charges.
6. Write the expression for electric potential at a point due to a short electric dipole mention one contrasting feature of electric potential of dipole at a point as compared to that due to a point charge.
7. Obtain the expression for effective capacitance of two capacitors connected in parallel.
8. Obtain the expression for effective capacitance of two capacitors connected in series.
9. Derive an expression for energy stored in a capacitor.

PART D Questions carrying FIVE marks each.

1. Derive an expression for electric potential due to an isolated point charge.
2. Derive an expression for the electric potential due to a short electric dipole

PART E (Numericals)Questions carrying FIVE marks each

1. A parallel plate capacitor with air between the plates, each plate has an area of 6 x 10 m² and the distance between the plates is 3 mm. Calculate the capacitance of the capacitor. If the capacitor is connected to 100 V supply, what is the charge on each plate of the capacitor
2. Two charges 3x 10°C and -2x 10°C are located 15 cm apart. At point on the line joining potential zero? Take the potential at infinity to be zero.
3. ABCD is a square of side 2 m, charges of 5 nC. +10 aC, -5 nC are placed at comers A. It and C respectively. What is the work done in transferring a charge of 5 uC from D to the point of intersection of diagonals?
4. When two capacitors are connected in series and connected across 4 kV line, the energy stored in the system is 8J. The same capacitors if connected in parallel across the same line, the energy stored is 36 J.Find the individual capacitances.
5. Two capacitors a capacitances 600 pF and 900 pF are connected in series across a 200 V supply. Calculate

(a) the effective capacitances of the combination

(b) pd across each capacitor 30. Calculated the charge on a parallel plate air capacitor consisting of two. Plates each of area 200 cm                          separated by 1mm when plates are charged to a potential of 800 volts. 31. A point charge of 20 pC is situated at a point O. A and                        B are points 0.05 m and 0.15 m away from the charge. Calculate the amount of work done to move an electron from B to A.

(c) total energy stored in the system.

6. The plates of a parallel plate capacitor have an area of 100 cm³ each and are separated by 3 mm. The capacitor is charged by

connecting it to a 400 V supply.

(a) Calculate the electrostatic energy stored in the capacitor.

(b) If a dielectric of dielectric constant 2.5 is introduced between the plates of the capacitor, then find the electrostatic energy

stored and also change in the energy stored.

 

33. In a circular parallel plate a capacitor radius of each plate is 5 cm and they are separated by a distance of 2 mm. Calculate the capacitance and the energy stored, when it is charged by connecting the battery of 200 V(given 8.854 x 102 Fm)..

 

34. ABCD is a square of side 1 m. Charges of +3 nc,-5 nc and +3 nc are placed at the corners A, B and C respectively. Calculate the work done in transferring a charge of 12 pc from D to the point of intersection of the diagonals?

 

35. A 400 pF capacitor charged by a 100 V de supply is disconnected from the supply and connected to another uncharged 400 pF capacitor, then

 

1. i) Calculate the common potential

 

(ii) Calculate the loss of energy