31) The electric field intensity on the surface of a charged conductor is

- zero
- directed normally to the surface
- directed tangentially to the surface
- directed along 45° to the surface

32) A capacitor having a capacitance of 30 μf is connected across a 200 V dc source. The charging current will be least

- initially
- when capacitor is half charged
- when capacitor is fully charged
- when capacitor is almost 90% charged

33) Out of the material given below, which has the highest dielectric strength

- glass
- mica
- oiled paper
- air

34) Two equal and similar charges are placed a finite distance apart. A third equal and dissimilar charge is placed midway between them. The third charge will be

- in stable equilibrium
- in unstable equilibrium
- neutralized
- oscillating

35) The positive terminal of a 12 V battery is earthed. The negative terminal will be at

- 0 V
- 12 V
- -12 V
- 24 V

36) A tiny particle carrying a charge of 0.3 C is accelerated through a potential difference of 1000 V. The kinetic energy acquired by the particle is

- 900 J
- 400 J
- 100 J
- 300 J

37) Two copper spheres A and B are of the same radii. Sphere A is hollow and Sphere B is solid. If both spheres are charged to the same potential

- Both will hold the same charge
- A will hold more charge as compared to B
- B will hold more charge as compared to A
- Both will not hold any charge

38) For dielectrics, flux is proportional to

- potential difference between electrodes
- resistivity of medium
- rate of change of potential difference
- rate of change of current

39) For a capacitance of 10 μf the potential difference is increased uniformly from 0 to 600 V in 2 seconds. The charging current must be

- 1 mA
- 3 mA
- 5 mA
- 10 mA

40) The capacitance between two plates increases with

- larger plate area and shorter distance between plates
- shorter plate area and shorter distance between them
- shorter plate area and higher applied voltage
- larger plate area, longer distance between plates and higher applied voltage

41) The charge on a capacitor is 1.5×10^{-2} coulombs when the potential difference across its plates is 750 V. The elastance of the capacitor will be

- 0.5 mega daraf
- 1 mega daraf
- 11.2 mega daraf
- 22.7 mega daraf

42) The current in a single element circuit leads the voltage 65° at all time. The circuit element is

- a resistor
- an inductor
- a capacitor
- any of the above

43) A parallel plate capacitor connected to a battery stores twice as much charge with a given dielectric as it does with air as dielectric, the susceptibility of the dielectric is

- 0
- 1
- 2
- 3

44) A capacitor is charged and source is then disconnected. When the plates are now separated

- charge changes
- charge and potential difference both change
- charge and potential difference remain constant
- potential difference changes

45) A sphere of 1 meter radius can attain a maximum potential of

- 1000 V
- 2 kV
- 30 kV
- 3×10
^{6}V