# CBSE CLASS 12 IMPORTANT ELECTROSTATICS QUESTIONS 2014

Questions having one mark each:

1. Write the S.I unit of
i. electric field intensity
ii. Electric dipole moment.
iii electric Potential
2. How does the coulomb force between two point charges depend upon the dielectric constant of the intervening medium?
3. Draw an equipotential surface for a system, consisting of two charges Q, -Q separated by a distance ‘r’ apart.
4. Show graphically the variation of charge ‘q’ with time’t’ when a condenser is charged.
5. What orientation of an electric dipole in a uniform electric field would correspond to stable equilibrium?
6. The potential energy of an electric dipole placed in a uniform electric field is minimum . What is the orientation of vectors p and E ?
7. State one situation in where potential is not zero but electric field intensity is zero .
8.  Does the electric potential increase or decrease along an electric line of force ?
9. A Gaussian surface encloses no charge . Does it mean that E = 0 on its surface ?
10. At what point is the electric dipole field intensity (i) parallel and (ii) antiparallel to dipole moment of the dipole ?
11. A 10µC charge is at the centre of a square of side 10 cm . Find the work done in moving the charge of 4 C between two diagonally opposite points on the square .
12. A charged air capacitor has stored energy U . What will be the energy stored when air is replaced by a dielectric of dielectic constant K , charge Q remains the same ?
13. The sequence of bands marked on carbon resistor are Red , Red , Red , Silver . Write the value of resistance with tolerance .
14. Define electric field intensity . Write its S.I. unit . Write the magnitude and direction of electric field intensity due to an electric dipole of length 2a at the mid point of the line joining the two charges.
15.. The force of attraction between two point charges placed at distance d apart in a medium is F. What should be the distance apart in the same medium so that the force of attraction between them becomes F/4 ?
16.Name the physical quantity whose SI unit is (i) coulomb/ volt (ii) newton/coulomb(iii) joule/coulomb.
17. What is the amount of work done in moving a 56 nC charge between two points 1 cm apart on an equipotential surface ?
18.What would be the work done if a point charge +q, is taken from a point A to the point B on the circumstance of a circle drawn with another point charge +q at the center ?

19.Two test charges are brought separately near a charge +Q.
Case 1: Test charge +q are brought to within a distance r from the charge +Q (i.e. to point A).
Case 2: Test charge +2q are brought to within a distance 2r from the charge +Q (i.e. to point B).
1. In which situation is the Electric Potential Energy of the system the greatest?
2. At which position is the Electric Potential the greatest