# Electrostatic Potential And Capacitance – Multiple Choice Questions

Q1. A Van de graph generator is used

1. to produce a charged particle.
2. to accelerate charged particles.
3. to accelerate uncharged particles.
4. to accelerate both charged and uncharged particles.

Q2. Positive mutual potential energy of a system containing two charges corresponds to

1. Repulsion
2. Attraction
3. Could not predict
4. None of the above

Q3. Materials in which outer electrons are loosely bound and free to move within the metal at normal temperature are called

1. Insulators
2. Semiconductors
3. Conductors
4. Superconductors

Q4. It requires 4 J of work to move a charge of 20 C from point A to point B, separated by a distance of 0.2 cm. The potential difference between A and B in volts

1. 80
2. 16
3. 5
4. 0.2

Q5. Choose the appropriate words to complete the sentence:

Equipotential surfaces are closer together in the region of fields and farther apart in the regions of fields.

1. Weak, Strong
2. Strong, Weak
3. Parallel, Perpendicular
4. Perpendicular, Parallel

Q6. For any charge configuration, an equipotential surface through a point is _____to the electric field at that point.

1.   Parallel
2. Perpendicular
3. At 45°
4. Anti-parallel.

Q7. Negative mutual potential energy corresponds to attraction between two charges

1. False
2. True
3. Can’t predict
4. None of the above

Q8. When a dielectric slab is introduced between the parallel plate capacitor, its capacitance

1. increases
2. decreases
3. remains the same
4. become zero.

Q9. The polarized dielectric is equivalent to

1. two charged surfaces with induced surface charge densities
2. one charged surface with induced surface charge density
3. zero surface charge density
4. non-zero volume charge density

Q10. Work done in carrying 2 C charge in a circular path of radius 2 m around a charge of 10 C is

1. Zero
2. 6.67J
3. 15 J
4. 60J

Q11. Two capacitors of capacitance of 4 μF and 8 μFare connected in series with a battery. The voltage across the 4 μF is 2 V. Compute the total battery voltage.

1. 3 V
2. 2 V
3. 5 V
4. 1 V

Q12. Direction of electric field on the equipotential surface is always

1. Parallel to the surface
2. At an angle of 45º to the surface
3. Normal to the surface
4. At an angle of 30º to the surface

Q13. In bringing an electron towards another electron, the electrostatic potential energy of the system

1. remains same
2. becomes zero
3. increases
4. decreases

Q14. A hollow metal sphere of radius 5 cm is charged such that the potential on its surface is 10 V. The potential at the centre of the sphere is

1. 0 V
2. 10 V
3. same as at point 5 cm away from the surface
4. same as at point 25 cm away from the surface

Q15. The displacement of charges inside the dielectric stops when

1. the external field becomes maximum
2. the external force on the charges of the molecules is balanced by the force due to internal fields
3. the internal force on the charges of the molecules is balanced by the forces due to the internal fields
4. none of the above

Q16. A proton is accelerated from rest through a potential of 500 volts. Its final kinetic energy is

1. 50 eV
2. 500 eV
3. 1000 eV
4. 2000 eV

Q17. How does the charge densities of conductors vary on an irregularly shaped conductor?

1. High at sharp and less at flat portion
2. Less at sharp and high at flat portion
3. Remains constant
4. Zero at sharp and high at flat portion

Q18. Direction of electric field just outside the surface of a charged conductor is

1. Parallel to the surface
2. Normal to the surface
3. Tangential to the surface
4. At an angle of 45º to the surface.

Q19. Work done in placing a charge of 8 x 10-18 C on a condenser of capacity 100 microfarad is

1. 16 x 10-32 J
2. 3.1 x 10-26 J
3. 4 x 10-10 J
4. 32 x 10-32 J

Q20. Three different capacitors are connected in series, then:

1. they will have equal charges
2. they will have same potential
3. both 1 & 2
4. none of these

Q21. The distance between the plates of a capacitor is d. What will be the new capacitance if a metal plate of thickness d/2 is introduced between the plates without touching them

1. remains the same
2. it will be half of its initial value
3. it will be double of its initial value
4. it will be thrice of its initial value

Q22. A uniformly polarized dielectric amounts to induced ______ charge density but no ______charge density.

1. volume, line
2. surface, volume
3. volume, surface
4. line, volume

Q23. The external field induces dipole moment by

1. only stretching
2. only re-orienting
3. stretching or re-orienting
4. ionizing

Q 24. The work done in moving a test charge over an equipotential surface is:

1. 1
2. Infinity
3. 0
4. -1

Q25. Electrostatic field is zero the conductor.

1. outside
2. Inside
3. On the surface
4. At the centre

Q26. Coulomb’s law is given by F = kq1q2rn, where n is

1. 1 / 2
2. 2
3. – 2
4. -1 / 2

Q27. Three capacitors of capacitances 3 μF are available. The minimum and maximum capacitances, which may be obtained, are

1. 1 μF, 12 μF
2. 1 μF,6 μF
3. 1 μF, 9 μF
4. 3 μF, 9 μF

Q28. The amount of work done in moving a unit positive charge through distance of 10 cm on an equipotential surface is

1. 10 cm
2. 1/10 cm
3. Zero
4. 100 joule

Q29. A bird sitting on a bare power cable does not feel any shock because of

1. Zero potential difference between its legs
2. High potential difference between its legs
3. Special property of its legs
4. Low potential difference between its legs

Q30. Let Q denote the charge, V denote potential difference and U denote stored energy. Of these quantities, capacitors in parallel must have the same:

1. Q only
2. V only
3. U only
4. Q and V only

Q31. The electric field inside a dielectric decreases, when it is placed in an external electric field. This happens due to

1. Electrostatic repulsion between atoms
2. Electrostatic attraction between atoms
3. Electrostatic shielding
4. Polarization

Q32. Optical analogue of an equipotential surface is

1. Wave motion of light
2. Wavefront of light
3. Interference of light
4. Reflection of light

Q33. If a unit charge is taken from one part to another part over an equipotential surface, then what is the change in electrostatic potential energy of the charge?

1. 1 J
2. 10 J
3. 100 J
4. 0 J

Q34. Metallic sphere of radius R is charged to potential V. Then charge q is proportional to

1. V
2. R
3. both V and R
4. none

Q35. Which of the following statements is not true for polar molecules?

1. the center of positive and negative charges are separated
2. permanent dipole moment
3. examples are oxygen and hydrogen molecules
4. examples are HCl or water molecules

Q36. The potential energy of a system containing only one point charge is

1. Zero
2. Infinity
3. Nonzero finite
4. None of the above

Q37. Electric field at the surface of a charged conductor is proportional to

1. Volume of the sphere
2. Area of the sphere
3. Surface charge density
4. Volume charge density

Q38. The extent of polarization depends on

1. Dipole potential energy
2. Thermal energy
3. Dipole potential energy and thermal energy
4. Kinetic energy of bound charges

Q39. Two capacitors of 20 μF and 30 μF are connected in series to a battery of 40 V. Calculate the charge on each capacitor.

1. 500 C
2. 478 C
3. 480 C
4. 450 C

Q40. Which of the following statement is not true for non-polar molecules?

1. the centers of positive and negative charges coincide
2. no permanent dipole moment
3. examples are oxygen and hydrogen molecules
4. examples are HCl or water molecules