Electrostatic Potential And Capacitance

15 Questions | Total Attempts: 2298

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Electrostatic Potential And Capacitance

Time: 30 Minute


Questions and Answers
  • 1. 
    A parallel plate capacitor has a capacitance of 50 pf in air and 105 pf when immersed in oil. The dielectric constant of the oil is:
    • A. 

      50/105

    • B. 

      1

    • C. 

      2.1

    • D. 
  • 2. 
    Three capacitors of capacitance 4µ F, 6µF and 12µF are connected first in series and then in parallel. What is the ratio of equivalent capacitance in the two cases?
    • A. 

      2 : 3

    • B. 

      1 : 11

    • C. 

      11 : 1

    • D. 

      1 : 3

  • 3. 
    A work of 100 joule is performed in carrying a charge of -5 coulomb from infinity to a particular point in an electrostatic field. The potential of this point is:
    • A. 

      100 V

    • B. 

      5 V

    • C. 

      -20 V

    • D. 

      20 V

  • 4. 
    Potential energy of two equal negative point charges 2µC each held 1m apart in air is:
    • A. 

      2 J

    • B. 

      2 eV

    • C. 

      4 J

    • D. 

      0.036 J

  • 5. 
    The electric potential at the surface of an atomic nucleus (Z = 50) of radius 9.0 x 10-15 m is:
    • A. 

      80 volt

    • B. 

      8 x  volt

    • C. 

      9 volt

    • D. 

      9 x  volt

  • 6. 
    Three different capacitors are connected in series. Then:
    • A. 

      They will have equal charges

    • B. 

      They will have same potential

    • C. 

      Both 1 & 2

    • D. 

      None of these

  • 7. 
    When air is replaced by a dielectric medium of constant K, the maximum force of attraction between two charges separated by a distance:
    • A. 

      Becomes times

    • B. 

      Increases K times

    • C. 

      Remains unchanged

    • D. 

      Decreases K times

  • 8. 
    A 2µF capacitor is charged to 100 volt and then its plates are connected by a conducting wire. The heat produced is:
    • A. 

      0.001 J

    • B. 

      0.01 J

    • C. 

      0.1 J

    • D. 

      1 J

  • 9. 
    A hollow metal sphere of radius 10 cm is charged such that the potential on its surface is 80 volt. The potential at the centre of the sphere is:
    • A. 

      8 volt

    • B. 

      800 volt

    • C. 

      80 volt

    • D. 

      Zero

  • 10. 
    The equivalent capacity of the combination C1 = C2 = C3 shown in figure is:
    • A. 

      2 C

    • B. 

      C

    • C. 

      C / 2

    • D. 

      None of these

  • 11. 
    The magnitude of electric field E in the annular region of a charged cylindrical capacitor.
    • A. 

      Is the same throughout

    • B. 

      Is higher near the outer cylinder than near the inner cylinder

    • C. 

      Varies as 1/r, where r is the distance from the axis

    • D. 

      Varies as 1/ , where r is the distance from the axis.

  • 12. 
    A parallel plate capacitor is made by stocking n equally spaced plates connected alternately. If the capacitance between any two plates is x, then the total capacitance is:
    • A. 

      Nx

    • B. 

      N/x

    • C. 

      X

    • D. 

      (n – 1) x

  • 13. 
    Three capacitors each of capacity 4 µF are to be connected in such a way that the effective capacitance is 6 µF. This can be done by:
    • A. 

      Connecting all of them in series

    • B. 

      Connecting all of them in parallel

    • C. 

      Connecting two in series and one in parallel

    • D. 

      Connecting two in parallel and one in series

  • 14. 
    A 800 µF capacitor is charged at the steady rate of 50 µC/sec. How long will it take to raise its potential to 10 volt?
    • A. 

      160 s

    • B. 

      50 s

    • C. 

      10 s

    • D. 

      500 s

  • 15. 
    If there are n capacitors in parallel connected to V volt source, then energy stored is equal to:
    • A. 

      CV

    • B. 

      C

    • C. 
    • D. 

      nC

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