Define electric flux and electric flux density. What is meant by negative flux? Explain with diagram. Write $\mathrm{SI}$ unit and dimensions of electric flux.

State Gauss’ theorem in electrostatics.
Apply this theorem to derive an expression for the electric intensity due to an infinite sheet of charge and hence deduce the expression for electric intensity due to two parallel oppositely charged thin infinite sheets of charge at a point

(i) between the sheets,

State Gauss’ theorem in electrostatics.
Apply this theorem to derive an expression for the electric intensity due to an infinite sheet of charge and hence deduce the expression for electric intensity due to two parallel oppositely charged thin infinite sheets of charge at a point

(ii) Outside the sheets.

Using Gauss’ theorem derive an expression for the electric intensity due to a charged thin spherical shell at

(i) external point,

(ii) surface point,

(iii) internal point.
Draw the graph showing the variation of electric intensity obtained as above with distance from the centre.