Objective Type Question Answers On Class 12 Physics Electrostatic Potential and Capacitance

1 If a +ve charge is moved from low to high potential region, the electric potential energy:

A decreases

B increases

C remain the same

D may increase or decrease

View Answer

Answer:increases

2 Minimum number of capacitor of 2µF each required to obtain a capacitance of 5µF will be:

A 4

B 3

C 5

D 6

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Answer:4

3 When a dielectric slab is introduced between the plates of a parallel plate capacitor which remains connected to a battery then charge on the plates relative to earlier charge is :

A more

B less

C less or may be more

D same

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Answer:more

4 A capacitor is connected to a cell of emf E having some internal resistance r, the potential across the:

A cell is < E

B cell is E

C cell is > E

D capacitor is E

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Answer:cell is E

5 Twenty seven drops of mercury are charged simultaneously to the same potential of 10 volts. What will be potential if all the charged drops are made to combine to form one large drop ?

A 180 V

B 90 V

C 120 V

D 45 V

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Answer:90 V

6 Two capacitors of capacitance 6 µF and 4 µF are put in series across a 120 V battery. What is the potential difference across the 4 µF capacitor ?

A 72 V

B 60 V

C 48 V

D zero

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Answer:72 V

7 Which of the following is blocked by a capacitor ?

A A.C.

B D.C.

C Both A.C. and D.C.

D Neither A.C. nor D. C

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Answer:D.C.

8 An electron initially at rest is accelerated through a potential difference of one volt. The energy gained by electron is:

A 1 J

B 1.6 × 10^-19 J

C 10^-19 J

D None of these

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Answer:1.6 × 10^-19 J

9 Two conducting spheres of radii r₁ and r₂ are equally charged. The ratio of their potential is

A (r₁/r₂)²

B (r₁r₂)²

C (r₁/r₂)

D (r₂/r₁)

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Answer:(r₁r₂)²

10 The capacitance of a capacitor will decrease if we introduce a slab of:

A copper

B aluminium

C zinc

D None of these

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Answer:None of these

11 The dimensions of fall of potential per unit distance are given by:

A [MLT^-3 A^-1]

B [ML²T^-2A^-1]

C [ML²T^-2A^-3]

D [MLT^-2A^-2]

View Answer

Answer:[ML²T^-2A^-3]

12 In which of the following forms is the energy stored in a capacitor?

A Charge

B Potential

C Capacitance

D Electric field

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Answer:Electric field

13 A bird sitting on a high power line:

A gets killed instantly

B gets a mild shock

C gets a fatal shock

D is not affected practically

View Answer

Answer:is not affected practically

14 The P.E. of an electric dipole is maximum when it makes an angle θ with electric field. The value of θ is :

A π/2

B π

C zero

D 3π/2

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Answer:π

15 The capacitance of earth, viewed as a spherical conductor of radius 6408 km is:

A 1420 µF

B 712 µF

C 680 µF

D 540 µF

View Answer

Answer:712 µF

16 Two capacitors of 3 µF and 6 µF are connected in series with a battery of P.d. 12 V. The P.d. across 3µF and 6µF

capacitors respectively will be :

A 8 V, 4 V

B 6 V, 6 V

C 4 V, 8 V

D 9 V, 3 V

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Answer:8 V, 4 V

17 The surface density of charge is measure:

A Cm^-1

B Cm^-2

C Cm^-3

D JC^-1

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Answer:Cm^-2

18 Choose the SI unit of electric potential energy :

A Joule

B Coulomb

C Netwon per coulomb

D Erg

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Answer:Joule

19 A dielectric is placed in between the two parallel plates of a capacitor as shown in the figure. The dielectric constant of the dielectric being K. If the initial capacity is C, then the new capacity will be:

Electrostatic Potential and Capacitance

A (K + l).C

B K.C

C

D (k – l) C

View Answer

Answer:

20 A polythene piece rubbed with wool is found to have a negative charge of 6.4 × 10^-9c. How many electrons have been transferred during the process?

A 4 × 10¹²

B 4 × 10¹¹

C 4 × 10¹⁰

D None of these

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