ELECTROSTATICS VERY SHORT ANSWER TYPE QUESTIONS

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5.Name two basic properties of electric charge.Ans. (i) Charge is conserved, and (ii) Charge is

quantized

6.The electric field lines never cross each other, why?Ans. If the electric field lines intersect at any point,

then there will be two directions of electric field at that point, which is impossible.

7.Draw lines of force to represent uniform electric field.Ans. The lines of force representing uniform electric

field are parallel and equidistant shown in figure.

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11. Depict the equipotential surfaces for a system of two identical positive point charges placed a distance ‘d’ apart.

Ans. Equipotential surfaces due to two identical charges is shown in figure.

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13. Draw an equipotential surface for a system consisting of two charges separated by a distance r in air.

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16.What is the shape of equipotential surface for a given point charge?Ans. Spherical.17.A 500C charge is at the centre of a square of side 10cm. Find the

work done in moving the charge of 10C between two diagonally opposite points on the square.

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18.What is the angle between the direction of electric field at any

i. Axial point and ii. Equatorial point due to an electric dipole?

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20.What is the function of a dielectric in a capacitor?Ans. Dielectric reduces the effective charge on plates and

hence increases the capacitance.

21.What is the effect on capacitance of introducing a dielectric slab between the plates of a parallel plate capacitor.

Ans. The introduction of dielectric slab between the plates of a parallel plate capacitor increases its capacitance.

22.How does the electric field inside a dielectric decrease when it is placed in an external electric field?

Ans. When a dielectric is placed in an external electric field, the charges are induced on the faces of dielectric which produce opposite electric field in the dielectric, thus net electric field is reduced.

23. Express dielectric constant in terms of capacitance.Ans.

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35. Two point electric charges of unknown magnitude and sign are placed at a distance ‘d’ apart. The electric intensity is zero at a point, not between the charges but on the line joining them. Write two essential conditions for this to happen.

Ans. (i) The charges should be of opposite nature. (ii) The charges should have different magnitudes.

36. A uniform electric field exists between two charged plates as shown in the figure. What should be the work done in moving a charge q along the closed rectangular path ABCDA.

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37.What should be the work done if a point charge +q is taken from a point A to the point B on the circumference drawn with another point +q at the centre?

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39.A and B are two conducting spheres of the same radius, A being solid and B hollow. Both are charged to the same potential. What will be the relation between the charges on the two spheres?

Ans. Potential V=Q/C . Charge resides on the surface of a conducting sphere. Therefore capacitance of both solid and hollow conducting spheres are equal, hence for same potential, charges on both spheres will be equal.

40. Two protons, A and B, are placed between two parallel plates having a potential difference V as shown in figure. Will the protons experience equal or unequal force?

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43.Name the dielectric whose molecules have (i) non-zero and (ii) zero dipole moment.

Ans.(i) The dielectric having non-zero dipole moment is water. (ii) The dipole having zero dipole moment is diamond (or

silicon).

44.At what points is the electric dipole field intensity parallel to the line joining the charges?

Ans.At axial points and at bisector points, the electric intensity of dipole is parallel to the line joining the charges.

45. The distance of the field point, on the equatorial plane of a small electric dipole is halved. By what factor does the electric field due to the dipole change?

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46Define dielectric constant of a medium. What is the value of dielectric constant for a metal?.

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48. A metallic sphere is placed in a uniform electric field as shown in the figure. Which path is followed by electric field lines and why?

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