Physics 12 MCQ of Electrostatic Potential and Capacitance – Chapter 2

Ques 1: Electrostatic potential V at a point, distant r from a charge q in air is

• q/r²
• q²/r
• q/r
• q²/r²

q/r

Ques 2: Work done in carrying an electron from A to B on an equipotential surface of one volt potential is

• 1 ev
• 10 eV
• 1 volt
• Zero

Zero

Ques 3: The correct relation between electric intensity E and electric potential V is

• E = -dV/dr
• E = dV/dr
• V = -dE/dr
• V = dE/dr

E = -dV/dr

Ques 4: A charge of 10μC lies at the centre of a square. Work done in carrying a charge of 2μC from one corner of square to the diagonally opposite corner is

• 20J
• 5J
• Zero
• 20μJ

Zero

Ques 5: A uniform electric field of 100 N/C exists in vertically upward direction. The decrease in electric potential as one goes up through a height of 5 cm is

• 20 V
• 120 V
• 5 V
• Zero

5 V

Ques 6: When a conductor is held in an electric field, the field inside the conductor is always

• positive
• negative
• constant
• zero

zero

Ques 7: Charge on a capacitor is doubled. Its capacity becomes k times, where

• k = 2
• k = 1
• k = 1/2
• k = 4

k = 1

Ques 8: Electrical capacity of earth is

• 1F
• 1μF
• 711μF
• 9×10⁹μF

711μF

Ques 9: When air in between the plates of a capacitor is replaced by mica of dielectric constant 6, its capacity

• remains unaffected
• reduced to 1/6th
• becomes 6 times
• non of the above

becomes 6 times

Ques 10: When a number of capacitors are connected in series between two points, all the capacitors possess same

• capacity
• potential
• charge
• none of the above

charge

Ques 11: When a number of capacitors are connected in parallel between two points, the equivalent capacitance

• increases
• decreases
• remains the same
• none of the above

increases

Ques 12: A condenser is charged to double its initial potential. The energy stored in the condenser becomes x times, where x =

• 2
• 4
• 1
• 1/2

4

Ques 13: When two capacitors charged to different potentials are connected by a conducting wire, what is not true?

• charge lost by one is equal to charge gained by the other
• potentail lost by one is equal to potentail gained by the other
• some energy is lost
• both the capacitor acquire a common potential

potentail lost by one is equal to potentail gained by the other

Ques 14: The relation between dielectric constant K and electric susceptibility χ of a material is

• K = χ
• K = 1+χ
• χ = K+1
• K² = (1+χ)(1−χ)

K = 1+χ

Ques 15: When charge is supplied to a conductor, its potential depends upon

• the amount of charge
• geometry and size of conductor
• both (a) and (b)
• only on (a)

both (a) and (b)

Ques 16: A parallel plate capacitor is charged by a battery. Once it is charged, battery is removed. Now a dielectric material is inserted between the plates of the capacitor. Which of the following does not change?

• electric field between the plates
• potential difference across the plates
• charge on the plates
• energy stored in the capacitor

Ques 17: A dipole is placed parallel to electric field. If W is the work done in rotating the dipole from 0° to 60°, then work done in rotating it from 0° to 180° is

• 2W
• 3W
• 4W
• W/2

4W

Ques 18: The variation of potential V with r and electric field with r for a point charge is correctly shown in the graphs

b

Ques 19: A charge Q is supplied to a metallic conductor. Which is true?

• Electric field inside it is same as on the surface
• electric potential inside is zero
• electric potential on the surface is zero
• electric potential inside is constant

electric potential inside is constant

Ques 20: A parallel plate capacitor C has a charge Q. The actual charges on the plates are

• Q, Q
• Q/2, Q/2
• Q, -Q
• Q/2, -Q/2

Q, -Q

Ques 21: Three capacitors of capacitances 1μF, 2μF and 3μF are connected in series and a potential difference of 11V is applied across the combination, then the potential difference across the plates of 1μF capacitor is

• 2V
• 4V
• 1V
• 6V

6V

Ques 22: The potential at the centre of the square is –

• zero
• kq/a
• kq/a²
• kq/2a²

zero

Ques 23: Two conducting spheres A and B of radii a and b respectively are at the same potential. The ratio of surface charge densities of A and B is

• b/a
• a/b
• a²/b²
• b²/a²

b/a

Ques 24: Work done to bring a unit positive charge un-accelerated from infinity to a apoint inside electri field is called

• Electric field
• Electric potential
• Capacitance
• Electric flux

Electric potential

Ques 25: Electric potential due to a point charge -q at distance x from it is given by

• Kq/x²
• Kq/x
• -Kq/x²
• -Kq/x

-Kq/x

Ques 26: Electric field is always

• Parallel to equipotential surface
• Perpendicular to equipotential surface
• It can be perpendicular and parallel as well
• It does not depend on distribution of charge

Perpendicular to equipotential surface

Ques 27: Electric field and electric potential inside a charged spherical shell :

• E = 0; V = 0
• E = 0; V ≠ 0
• E ≠ 0; V = 0
• E ≠ 0; V ≠ 0

E = 0; V = 0

Ques 28: Shape of equipotential surface in uniform electric field will be :

• spherical normal to electric field
• random
• circular normal to electric field
• equidistant planes normal to electric field

equidistant planes normal to electric field

Ques 29: On reducing potential across a capacitor, its capacitance

• decreases
• increases
• remains constant
• first increases then decreases

increases

Ques 30: Energy stored in a charged capacitor is given by

• U = CV/2
• U = CV²
• 2CV²
• VC²/2

U = CV/2

Ques 31: If n number of equal capacitors each of capacitance C are connected in series, then equivalent capacitance will be given as :

• nxC
• C/n
• n+C
• n²C

nxC

Ques 32: Capacitance of parallel plate capacitors when there is no medium between the plates is C₀. If capacitor is now completely filled with dielectric matter of constant K, the capacitance would be :

• C₀/K
• KC₀
• K²C₀
• 2KC₀

KC₀