16) Two charged spheres of radii 10 cm and 15 cm are connected by a thin wire. No current will flow if they have

- the same charge
- the same energy
- the same field on their surface
- the same potential

17) The relative permittivity of most materials lies between

- 20 and 100
- 10 and 20
- 100 and 200
- 1 and 10

18) If the relative permittivity of the medium increases, the electric intensity at a point due to a given charge

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

19) An electric field can deflect

- x-rays
- neutrons
- α-particles
- γ-rays

20) Electric lines of force enter or leave a charged surface at an angle of

- 90°
- 30°
- 60°
- depends upon surface condition

21) One thousand electrons, each of which carries a charge of -1.6×10^{-12} coulomb are removed from an initially neutral pitch ball. The resulting charge on the pitch ball is

- 1.6×10
^{-15}coulomb - 1.6×10
^{-23}coulomb - -1.6×10
^{-15}coulomb - -1.6×10
^{-23}coulomb

22) When the potential difference across the electric field intensity between the parallel plate air capacitor is doubled, plates

- is not change
- is halved
- is doubled
- is independent of the potential difference

23) Midway between two equal and similar charges, a third equal and similar charge is placed, then this third charge will

- remain in stable equilibrium
- be in unstable equilibrium
- not be in equilibrium
- will move out of the field of influence of the two charges

24) One volt is the same as

- one joule
- one coulomb
- one joule/coulomb
- one coulomb/joule

25) One farad is the same as

- one coulomb/volt
- one joule/volt
- one joule/coulomb
- one coulomb/joule

26) When a dielectric is placed in an electric field, the field strength

- increases
- decreases
- remains unchanged
- reduces to zero

27) Electric potential is a

- scalar quantity
- vector quantity
- dimensionless quantity
- none of the above

28) The potential at a point due to a charge is 9 V. If the distance is increased three times, the potential at that point will be

- 27 V
- 3 V
- 12 V
- 18 V

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

- 10 V
- 0 V
- same as at point 5 cm away from the surface
- same as at point 25 cm away from the surface

30) If a unit charge is taken from one point to another over an equipotential surface, then

- work is done on the charge
- work is done by the charge
- work on the charge is constant
- no work is done