Electricity

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1)   The capacitance of a parallel plate capacitor can be varied by

  • [A] changing the dielectric medium only
  • [B] changing the distance between the plates only
  • [C] changing the overlapping area of the plates only
  • [D] All of the above

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All of the above

2)   For making a capacitor, it is better to select a dielectric having

  • [A] high permittivity
  • [B] permittivity slightly more than of air
  • [C] permittivity same as that of air
  • [D] low permittivity

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high permittivity

3)   The power dissipated in a pure capacitor is

  • [A] proportional to the value of capacitance
  • [B] zero
  • [C] proportional to applied voltage
  • [D] Both (a) and (c)

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zero

4)   If C be the capacitance, V be the potential difference and I be the current, then I / CV will have the unit of

  • [A] power
  • [B] reactive power
  • [C] time
  • [D] frequency

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frequency

5)   If the dielectric of a capacitor is replaced by conducting material

  • [A] the plate will get short circuited
  • [B] the capacitor will get heated up due to eddy currents
  • [C] the capacitance value of the capacitor will shoot upto very high value
  • [D] the capacitor can store infinite charge

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the plate will get short circuited

6)   A variable capacitance is one whose capacitance

  • [A] changes with voltage
  • [B] changes with temperature
  • [C] can be changed manually or by mechanical force
  • [D] changes with time

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can be changed manually or by mechanical force

7)   A capacitor having a capacitance of 40 µF is connected across 250 V DC source. The charging current will be least

  • [A] initially
  • [B] when capacitor is almost 25% charged
  • [C] when capacitor is half charged
  • [D] when capacitor is fully charged

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when capacitor is fully charged

8)   Internal heating of a capacitor is usually attributed to

  • [A] plate vibration
  • [B] dielectric charge
  • [C] leakage reisitance
  • [D] electron movement

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leakage reisitance

9)   In a capacitive circuit

  • [A] a steady value of applied voltage causes discharge
  • [B] decrease in applied voltage makes a capacitor charge
  • [C] an increase in applied voltage make a capacitor charge
  • [D] None of the Above

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an increase in applied voltage make a capacitor charge

10)   The sparking between two electrical contacts can be reduced by inserting a

  • [A] capacitor in parallel with contacts
  • [B] capacitor in series with each contacts
  • [C] resistance in line
  • [D] None of the Above

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capacitor in parallel with contacts

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