Review Questions

1.       Sketch a graph showing the variation of resistivity of carbon with temperature.

2.       Two copper spheres of same radii , one hollow and another solid are charged to same potential. Which of the two will have more  charge.

3.       An electric dipole of dipole moment   50X10^-6 C m is enclosed by a  surface. What is the net flux  coming out of the surface.

4.       Explain why two electric field lines cannot cross each other at any point.

5.       Sketch the equipotential surface for a system of dipole.  

6.       Determine the current through a carbon resistor having colour rings red,green and red respectively when connected to 10 V battery.

7.       Obtain the relation between drift velocity and relaxation time. Also show that current density is directly proportional to relaxation time.

8.       By using Gauss’s theorem, derive an expression for electric field due to a infinitely long straight uniformly charged conductor.

9.       A battery of emf 10V and internal resistance 2 Ω is connected to a resistor. If the current in the circuit is 0.5 A, what is the resistance of the resistor? What is the terminal voltage of the battery when the circuit is closed.

10.   (i)  Define the term  electric dipole moment. Is it scalar or vector? Give its SI unit.             

               (ii) Deduce an expression for electric field at a point on equatorial plane of an dipole of length 2a.  

                                                                                OR

(i) Define capacitance. Give its SI unit.

(ii) Obtain an expression for the capacitance of a parallel plate capacitor when a dielectric slab of thickness “t” is introduces between the plates of capacitor.