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Friday, 16 October 2015

Capacitance - Multiple Choice Questions

Capacitance - Multiple Choice Questions Points : Capacitance multiple choice questions and answers, electrical objective type question answers, mcqs 1. A capacitor opposes
(i) change in current
(ii) change in voltage
(iii) both change in current and voltage
(iv) none of the above

2. Capacitance of a parallel-plate capacitor does not depend upon
(i) area of plates
(ii) medium between plates
(iii) separation between plates
(iv) metal of plates

3. An additional name for relative permittivity is
(i) dielectric strength
(ii) breakdown voltage
(iii) specific inductive capacity
(iv) potential gradient

4. If a multiplate capacitor has 7 plates both of area 6 cm2, then
(i) 6 capacitors will be in parallel
(ii) 7 capacitors wilt be in parallel
(iii) 7 capacitors will be in series
(iv) 6 capacitors will be in series

5. The capacitance of a capacitor is relative permittivity.
(i) directly proportional to
(ii) inversely proportional to
(iii) independent of
(iv) directly proportional to square of

6. Two capacitors of capacitances 3 μf and 6 μF in series will contain a whole capacitance of
(i) 9μF
(ii) 2μF
(iii) 18μP
(iv) 24 μF

7. An air capacitor has similar dimensions as that of a mica capacitor. If capacitance of mica capacitor is 6 times that of air capacitor, then relative permittivity of mica is
(i) 36
(ii) 12
(iii) 3
(iv) 6

8. Capacitance of a parallel-plate capacitor depends upon:
(i) the type of metals use
(ii) separation among plates
(iii) thickness of plates
(iv) potential difference among plates

9. Most Convenient way of achieving large capacitance is through using
(i) multiplate construction
(ii) decreased distance between plates
(iii) air as dielectric
(iv) dielectric of low permittivity

10. Two capacitors contain capacitance 25 μF while in parallel and 6 μF when in series. Their creature capacitances are
(i) 12μF and 13μF
(ii) 15μF and 10μF
(iii) 10μF and 8μF
(iv) none of above

11. Which of following does not change while a glass slab is introduce among plates of a charged parallel plate capacitor?
(i) electric charge
(ii) electric energy
(iii) capacitance
(iv) electric field intensity

12. Plates of a charged parallel-plate capacitor are pulled separately. Now
(i) p.d. will remain unchanged
(ii) p.d. will decrease
(iii) p.d. will increase
(iv) the capacitance will increase

13. Empty space among plates of a capacitor Es filled by a liquid of dielectric stable K. The capacitance of capacitor
(i) increases by a factor K
(ii) decreases by a factor K
(iii) increases by a factor K2
(iv) decreases by a factor K2

14. 64 drops of radius r combine to form a better drop of radius R. Ratio of capacitances of bigger to lesser drop is
(i) 1:4
(ii) 2:1
(iii) 1:2
(iv) 4:1

15. In order to enlarge capacitance of a parallel-plate capacitor, one should initiate among the plates a sheet of
(i) mica
(ii) tin
(ii) copper
(iv) stainless steel

16. Capacitor of 20 μF charged to 500 is attached in parallel by another capacitor of 10 μF capacitance and charged to 200 V. The ordinary potential is
(i) 200 V
(ii) 250 V
(iii) 400 V
(iv) 300 V

17. Parallel plate capacitor is prepared through stacking n evenly spaced plates attached alternately. If capacitance among any two plates is C. then the resulting capacitance is
(i) C
(ii) nC
(iii) (n— 1)
(iv) (n + 1) C

18. Capacitor of 1 μF is charged to a potential of 50 V. It is now linked to an uncharged capacitor of capacitance 4 μF. The frequent potential is
(i) 50V
(ii) 20V
(iii) 15V
(iv) 10V

19. Parallel-plate air capacitor is engrossed in oil of dielectric constant 2. The electric field among the plates is
(i) increased 2 times
(ii) increased 4 times
(iii) decreased 2 times
(iv) none of above

20. Two capacitors of capacitances 2 pF and 6 pF are attached in parallel across a 120 V d.c. source. The sum total of charges on capacitors is
(i) 15 pC
(ii) 1980 pC
(iii) 180 pC
(iv) 960 pC

21. Two insulated charge spheres of radii 20 cm and 25 cm in that order and having an equal charge Q are connected with a copper wire and are then separated. Then,
(i) both spheres will have the same charge
(ii) charge on 20 cm sphere is greater
(iii) charge on 25 cm sphere is greater
(iv) charge on each will be 2 Q.

22. Three capacitors of capacitances 3 μF 9 μF and 18 μF are attached once in series and another time in parallel. Ratio of equivalent capacitances in two cases (Cs /CP) will be
(i) 1:15
(ii) 1:3
(iii) 1:9
(iv) 1:12

23. A capacitor of 100 pF is charge to 100 V. The charge accumulate on plates of the capacitor is
(i) 10-6 C
(ii) 6 x 10-2 C
(iii) 10-8 C
(iv) 6 x 10-4 C

24. Dielectric is introduce among plates of a capacitor kept at & constant likely difference. The charge on the capacitor
(i) increases
(ii) decreases
(iii) remains the same
(iv) none of above

25. Force acting on a charged particle kept among plates of a charged capacitor is F. If one of plates of the capacitor is detached force acting on similar particle will become
(i) F/2
(ii) 0
(iii) F
(iv) 2F

26. Capacitor is charged during a p.d. of 200 V and possesses charge of 0.1 C. When discharged, it would discharge an energy of
(i) 20 J
(ii) 1 J
(iii) 10J
(iv) 12J

27. A parallel-plate capacitor has plate separation t and a capacitance of 100 pF. If a metallic foil of width t/3 is introduce among the plates, the capacitance would become
(i) 100pF
(ii) 180pF
(iii) 200/3 pF
(iv) 150 pF

28. Capacitance of a parallel plate capacitor is 5μF. When a glass plate is inserted between its two plates. its potential reduces to 1/8 of original value. The value of dielectric stable of glass is
(i) 4
(ii) 8
(iii) 40
(iv) 16

29. Parallel-place capacitor by air as middle among places has a capacitance of 10 μF. Area of the capacitor is separated into equivalent halves and filled by two media have dielectric constant K1 = 2, K2 = 4. The capacitance of system will now be
(i) 10μF
(ii) 20μF
(iii) 40μF
(iv) 30 μF

30. Equal capacitance of parallel combination of two capacitors is four times their equal capacitance while linked in series. This means that
(i) there capacitances are equal
(ii) then capacitances are 2 μF and 4 μF
(iii) their capacitances are 0.5 μF and 1 μF
(iv) none of the above

31. Five equal capacitors linked in series contain a resultant capacitance of 4 μF. When these capacitors are attached in parallel and charged to 400 V d.c., total energy stored is
(i) 16J
(ii) 8J
(iii) 24J
(iv) 9J

32. The charge of a capacitor during a resistance follows
(i) linear law
(ii) square law
(iii) exponential law
(iv) none of above

33. Two capacitors, every of capacitance 1 μF, are attached in parallel and then charged by 200 V d.c. supply. Energy stored with the system is (i) 0.02 J
(ii) 0.1 J
(iii) 0.04 J
(iv) 0.08 J

34. Two capacitors of capacitances 0.3 μF and 0.6 μF in that order are connected in series. The combination is linked across a potential difference of 6 V. Ratio of energies store through the capacitors will be
(i) 4
(ii) 2
(iii) ¼
(iv) 1/8

35. You are given 4 capacitors, each of capacitance 12μf. How would you attach given capacitors to attain a capacitance of 9μF?
(i) all in series
(ii) all in parallel
(iii) 3 in parallel and 1 in series
(iv) 2 in parallel and other two in series

36. N drops of mercury of equivalent radii and possessing equal charges join to form a bigger drop. The ratio of capacitances of bigger drop to lesser drop is
(i) N1/3
(ii) N
(iii) N2/3
(iv) N33/2

37. Capacitor is charged by a battery. While the capacitor is have air core, the charge on plates is 70 μC. When the similar capacitor has mica core of dielectric 7, charge on the plates is
(i) 10μC
(ii) 70μC
(iii) 700 μC
(iv) 490 μC

38. Three capacitors of capacitances 6 μF every are available. Minimum and maximum capacitances which can be obtain are
(i) 6μF, 18μF
(ii) 2μ 18μF
(iii) 9μF. 27 μF
(iv) none of above

39. Two capacitors of capacitances 4 μF and 6 μF are linked in parallel. This combination is then linked in series to a third capacitor. If the equal capacitance of arrangement is 10/3 μF, capacitance of the third capacitor is
(i) 2μF
(ii) 5μF
(iii) 9μF
(iv) 4μF

40. The capacitance of earth assume it to be a spherical conductor of radius 6400 km is
(i) 725 μF
(ii) 616 μF
(iii) 1315 μF
(iv) 711 μF

41. If you require a capacitor by C = 0.25 μF and you contain simply ones in storeroom by capacitance of 1 μF, how will you obtain the preferred capacitance?
(i) connect four available capacitors in series
(ii) connect four available capacitors in parallel
(iii) connect two available capacitors in parallel
(iv) none of above

42. Capacitor of 0.1 μF is charged and then discharged during a 10 MΩ resistor. The time in which the capacitor lose half of its potential is
(i) 1 s
(ii) 0.5 s
(iii) 0.693 s
(iv) 1.25.s

43. A 6 μF capacitor is so charged that the possible dissimilarity across its plates becomes 50 V. The work done in process is
(i) 7.5x 103J
(ii) 3x 10-3J
(iii) 6.5 x 102J
(iv) 7.5 x 10-3J

44. A gang capacitor is a changeable capacitor in which capacitance is distorted through changing
(i) distance between plates
(ii) plate area
(iii) both (i) and (ix)
(iv) dielectric

45. Capacitance of a circular capacitor is 1μF. If spacing among two spheres is 1 mm, radius of the outer sphere is
(i) 0 6m
(ii) 3m
(iii 25 m
(iv) 4.5 in

46. The equal capacitance of two capacitors in parallel is four times their equal capacitance in series. This means that
(i) the capacitances of the two capacitors are equal
(ii) the capacitances are 1μF and 4μF
(iii) the capacitances are 6μF and 9μF
(iv) none of above

47. Parallel-plate capacitor is certain a charge of 3 μC. A dielectric of relative permittivity 3 is inserted among plates of the capacitor so as to fill the space among plates wholly. The induce accuse on each face of dielectric is
(i) 6μC
(ii) 2μC
(ii) 9μC
(iv) 4μC

48. The plate parting of a capacitor is 0.02 mm filled completely by a dielectric medium. If dielectric strength of material is 20 kV/mm, the utmost voltage rating of capacitor is
(i) 400V
(ii) 100V
(iii) 1600 V
(iv) 800V

49. An RC circuit is linked to a 300 V d.c. source, Voltage across capacitor after 1 time stable is
(i) 200 V
(ii) 126.5 V
(iii) 170.2 V
(iv) 189.6 V

50. Series circuit has a capacitance of 10 μF and resistance 3 MΩ. It is linked to a d.c. source of emf. 100 V. The rate of steady status current is
(i) 20μA
(ii) zero
(iii) 10 A
(iv) 20 A

51. Trimmer is a changeable capacitor in which capacitance is altered by changing
(i) distance between plates
(ii) plate area
(iii) both (i) and (ii)
(iv) dielectric

52. Capacitor of 025 μF charge to a definite potential is discharged through 40 MΩ resistor. Time taken through the one-third charge to escape is
(i) 6.3s
(ii) 4.1s
(ii) 3.9s
(iv) 2.5s

53. Capacitance of an remote sphere is 5 μF in ar. If it is placed in a medium of relative permittivity 5. then its capacitance will be
(i) 5μF
(ii) 1μF
(iii) 2.5 μF
(iv) 25 μF

54. In a changeable capacitor, the dielectric use is usually
(i) air
(ii) solid
(iii) electrolyte
(iv) none of the above

55. Metal sphere mount on an insulating rod carries a charge of 6 nC when its potential is 200 V higher than surroundings. Capacitance of capacitor produced through sphere and surroundings is
(i) 30pF
(ii) 20pF
(iii) 40pF
(iv) 60pF

56. Capacitor of 20 μF charge to 500 V is linked in parallel with another of 10 μF capacitance charged to 200 V. The failure of energy is
(i) 2.3J
(ii) 4.6J
(iii) 0.3J
(iv) 1.2J

57. While a capacitor is charge as of a battery
(i) the two plates acquire exactly equal and opposite charges
(ii) the charge on positive plate is more
(iii) the charge on negative plate is more
(iv) cannot be predicted

58. Two the same capacitors are linked in parallel and charged to a potential of V. They are divided and then linked in series, The p.d. across series combination is
(i) V
(ii) 4V
(iii) 3V
(iv) 2V

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