﻿ Engineering Entrance Exam Question and Answers | Electric Charges and Fields - Zigya

## Previous Year Papers

Download Solved Question Papers Free for Offline Practice and view Solutions Online.

## Test Series

Take Zigya Full and Sectional Test Series. Time it out for real assessment and get your results instantly.

## Test Yourself

Practice and master your preparation for a specific topic or chapter. Check you scores at the end of the test.

# Electric Charges and Fields

#### Multiple Choice Questions

101.

Two spheres of electric charges + 2 nC and −8 nC are placed at a distance d apart. If they are allowed to touch each other, what is the new distance between them to get a repulsive force of same magnitude as before ?

• d

• $\frac{\mathrm{d}}{2}$

• $\frac{3\mathrm{d}}{4}$

• $\frac{4\mathrm{d}}{3}$

102.

Three point charges of + 2q, + 2q and − 4q are placed at the corners A, B and C of an equilateral triangle ABC of side x. The magnitude of the electric dipole moment of this system is

• 2qx

• 3qx

103.

64 small drops of mercury, each of radius r and charge q coalesce to form a big drop. The ratio of the surface density of charge of each small drop with of the big drop is

• 64 : 1

• 1 : 64

• 1 : 4

• 4 : 1

104.

Three point charges are placed at the corners of an equilateral triangle. Assuming only electrostatic forces are acting. Then the system

• will be in equilibrium if the charges rotate about the centre of the triangle

• can never be in equilibrium

• will be in equilibrium if the charges have the same magnitudes but different sign

• will be in equilibrium if the charges have different magnitude and different signs.

105.

Two copper balls, each weighing 10 g are kept in air 10 cm apart. If one electron from every 106 atoms is transferred from one ball to the other, the Coulomb force between them is (atomic weight of copperis 63.5)

• 2.0 × 104 N

• 2.0 × 1010 N

• 2.0 × 106 N

• 2.0 × 106 N