31. Six capacitors of different capacitances C_{1}, C_{2}, C_{3}, C_{4}, C_{5} and C_{6} are connected in series. C_{1} > C_{2} > C_{3} > C_{4} > C_{5} > C_{6}. What is the total capacitance almost equal to?

- C
_{1}

- C
_{3}_{ } - C
_{4}_{ } - C
_{6}_{ }

32. Image theory is applicable to problems involving

- electrostatic field only
- magnetostatic field only
- both electrostatic and magnetostatic fields
- neither electrostatic nor magnetostatic field

33. Where is the Laplace’s equation valid?

- Only in free space
- Only in conductors
- Only in charge free dielectric regions
- Only in cavities bounded on all sides by conducting walls

34. Which one of the following statements does not state that electrostatic field is conservative?

- The curl of is identically zero.
- The potential difference between two points is zero.
- The electrostatic field is a gradient of a scalar potential.
- The work done in a closed path inside the field is zero.

35. Which one of the following gives the approximate value of the capacitance between two spheres, whose separation is very much larger than their radii R?

- 2π/ε
_{o}R - 2πε
_{o}R - 2πε
_{o}/R - 4πε
_{o}/R

36. A flat slab of dielectric, ε_{r} = 5 is placed normal to a uniform field with a flux density D = 1 C/m^{2}. The slab is uniformly polarized. What is the polarization P of the slab in Coulomb/m^{2}?

- 0.8
- 1.2
- 4
- 6

37. What is the value of total electric flux coming out of a closed surface?

- Zero
- Equal to volume charge density
- Equal to the total charge enclosed by the Surface
- Equal to the surface charge density

38. A plane slab of dielectric having dielectric constant 5, placed normal to a uniform field with a flux density of 2 C/m^{2}, is uniformly polarized. The polarization of the slab is

- 1.6 C/m
^{2} - 0.4 C/m
^{2} - 6.4 C/m
^{2} - 2.0 C/m
^{2}

39. A copper wire carries a conduction current of 1.0 A at 50 Hz. For copper wire ε = ε_{o}, μ = μ_{o}, σ = 5.8 x 10 mho/m. what is the displacement current in the wire?

- 2.8 x 10 A
- 4.8 x 10
^{-11}A - 1 A
- It cannot be calculated with the given data

40. The relation between electric intensity E, voltage applied V and the distance between the plates of a parallel plate condenser is

- E = V/d
- E = V x d
- E = V/(d)
^{2} - E= V x (d)
^{2}

41. A medium behaves like dielectric when the

- displacement current is just equal to the conduction current
- displacement current is less than the conduction current
- displacement current is much greater than the conduction current
- displacement current is almost negligible

42. When air pocket is trapped inside a dielectric of relative permittivity ‘5’, for a given applied voltage across the dielectric, the ratio of stress in the air pocket to that in the dielectric is equal to

- 5
- 1/5
- 5-1
- 1+5