The potential gradient is a:

  • vector quantity.

  • scalar quantity.

  • conversion factor.

  • constant.

The electric potential V at a point P(x, y, z) in space is given by V=4x2 volt. The electric field at a point (1m, 0, 2m) in V/m is:

  • 8 along the -ve x-axis

  • 8 along the +ve x-axis

  • 16 along the -ve x-axis

  • 16 along the +ve x-axis

Determine the electric field strength vector if the potential of this field depends on x, y coordinates as V=10axy.

  •  10 a (yi^+xj^)

  •  -10 a (yi^+xj^)

  •  -a (yi^+xj^)

  •  -10 a (xi^+yk^)

If on the x-axis, the electric potential decreases uniformly from 60 V to 20 V between x=-2 m to x=+2 m, then the magnitude of electric field at the origin:

  • must be 10 V/m.

  • may be greater than 10 V/m.

  • is zero.

  • is 5 V/m.

An infinite conducting sheet has a surface charge density σ. The distance between the two equipotential surface is r. The potential difference between these two surfaces is:

  •  σr2ε0

  •  σrε0

  •  σε0r

  •  σ2ε0r

If an α-particle and a proton are accelerated from rest by a potential difference of 1 megavolt, then the ratio of their kinetic energies will be:

  •  12

  • 1

  • 2

  • 4

Three charges -q, Q and -q are placed respectively at equal distances on a straight line. If the potential energy of the system of three charges is zero, then what is the ratio of Q:q?

  • 1: 1

  • 1: 2

  • 1: 3

  • 1: 4

A particle A has charge +q and another particle B has charge +4q with each of them having the same mass m. When allowed to fall from rest through the same electric potential difference, the ratio of their speeds vAvB will become:

  • 1: 2

  • 2: 1

  • 1: 4

  • 4: 1

If 50 joule of work must be done to move an electric charge of 2 C from a point where the potential is -10 volt to another point where the potential is V volt, then the value of V is:

  • 5 V

  • -15 V

  • +15 V

  • +10 V

A proton has a mass 1.67×10-27 kg and a charge +1.6×10-19 C. If the proton is accelerated through a potential difference of 1 million volts, then the kinetic energy is:

  •  1.6×10-15 J

  •  1.6×10-13 J

  •  1.6×10-21 J

  •  3.2×10-13 J

Two electrons are moving towards each other, each with a velocity of 106 m/s. What will be the closest distance of approach between them?

  •  1.53×10-8 m

  •  2.53×10-10 m

  •  3.53×10-6 m

  • Zero

1000 small water drops, each of capacitance C, join together to form one large spherical drop. The capacitance of the bigger sphere is:

  • C

  • 10C

  • 100C

  • 1000C

Two similar conducting balls having charges +q and -q are placed at a separation d from each other in the air. The radius of each ball is r and the separation between their centres is d(d>>r). Calculate the capacitance of the two-ball system.

  •  4πε0r

  •  2πε0r

  •  4πlogeε0rd

  •  4πlogerd

Two parallel plate capacitors have their plate areas 100 cm2 and 500 cm2 respectively. If they have the same charge and potential and the distance between the plates of the first capacitor is 0.5 mm, then the distance between the plates of the second capacitor is:

  • 0.10 cm

  • 0.15 cm

  • 0.20 cm

  • 0.25 cm

A dielectric slab of dielectric constant K is placed between the plates of a parallel plate capacitor carrying charge q. The induced charge q' on the surface of the slab is given by:

  •  q'=q-qK

  •  q'=-q+qK

  •  q'=q1K+1

  •  q'=-q1+1K

The following arrangement consists of five identical metal plates parallel to each other. The area of such plate is A and separation between the successive plates is d. The capacitance between P and Q is:

  •  5ε0Ad

  •  73ε0Ad

  •  43ε0Ad

  •  53ε0Ad

The charge on the 6 μF capacitors in the circuit shown is:

  •  540 μC

  •  270 μC

  •  180 μC

  •  90 μC

In a region of constant potential:
a. the electric field is uniform
b. the electric field is zero
c. there can be no charge inside the region
d. the electric field shall necessarily change if a charge is placed outside the region

  • (b, c)
  • (a, c)
  • (b, d)
  • (c, d)

In the circuit shown below C1=10μF, C2=C3=20μF and C4=40μF. If the charge on C1 is 20μC then potential difference between X and Y is 

  • 2 V

  • 3 V

  • 6 V

  • 3.5 V

A capacitor with plate separation d is charged to V volts. The battery is disconnected and a dielectric slab of thickness d2 and dielectric constant '2' is inserted between the plates. The potential difference across its terminals becomes:

  • V

  • 2 V

  •  4V3

  •  3V4

An uncharged parallel plate capacitor having a dielectric of constant K is connected to a similar air-cored parallel capacitor charged to a potential V. The two capacitors share charges and the common potential is V'. The dielectric constant K is:

  •  V'-VV'+V

  •  V'-VV'

  •  V'-VV

  •  V-V'V'

A battery does 200 J of work in charging a capacitor. The energy stored in the capacitor is:

  • 200 J

  • 100 J

  • 50 J

  • 400 J

Two identical capacitors are connected in parallel across a potential difference V. After they are fully charged, the positive plate of the first capacitor is connected to the negative plate of the second and the negative plate of the first is connected to the positive plate of the other. The loss of energy will be:

  •  12CV2

  •  CV2

  •  14CV2

  • Zero

Figure shows equipotential surfaces for a two charges system. At which of the labeled points will an electron have the highest potential energy?

   

  • Point A

  • Point B

  • Point C

  • Point D

A thin, metallic spherical shell contains a charge Q on it. A point charge q is placed at the centre of the shell and another charge q1 is placed outside it as shown in the figure. All the three charges are positive. The force on the central charge due to the shell is:

 

  • towards left

  • towards right

  • upward

  • zero

In a certain region of space, the electric field is zero. From this we can conclude that the electric potential in this region is:

  • positive

  • negative

  • constant

  • zero

An uncharged aluminium block has a cavity within it. The block is placed in a region permeated by a uniform electric field which is directed upwards. Which of the following is a correct statement describing conditions in the interior of the block's cavity?

  • The electric field in the cavity is directed upwards

  • The electric field in the cavity is directed downwards

  • There is no electric field in the cavity

  • The electric field in the cavity is of varying magnitude and is zero at the exact center.

A capacitor is filled with an insulator and a certain potential difference is applied to its plates. The energy stored in the capacitor is U. Now the capacitor is disconnected from the source and the insulator is pulled out of the capacitor. The work performed against the forces of the electric field in pulling out the insulator is 4U. Then dielectric constant of the insulator is:

  • 4

  • 8

  • 5

  • 3

An insulator plate is passed between the plates of a capacitor. Then current(outside the capacitor):

  • Always flows from A to B

  • Always flows from B to A

  • First flows from A to B and then from B to A

  • First flows from B to A and then from A to B

For a uniform spherical positive distribution of charge over volume of radius R, the potential will be maximum:

  • on the surface

  • at the center

  • at a distance R2 from the surface

  • at a distance 3R2 from the surface

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