# Numerical on Coulomb’s Law

Numerical : –

Example 1. Find out the electrostatics force between two point charges placed in air (each of +1 C) if they are separated by 1m .

Example 2. Two particles having charges q1 and q2 when kept at a certain distance, exert a force F on each other. If the distance between the two particles is reduced to half and the charge on each particle is doubled then what will be the force between the particles.

Example 3. A particle of mass m carrying charge q1 is revolving around a fixed charge –q2 in a circular path of radius r. Calculate the period of revolution and its speed also.

Example 4. A point charge qA = + 100 µc is placed at point A (1, 0, 2) m and an another point charge qB = +200µc is placed at point B (4, 4, 2) m. Find :
(i) Magnitude of Electrostatic interaction force acting between them
(ii) Find (force on A due to B) and (force on B due to A) in vector form.

Example5. If the distance between two equal point charges is doubled and their individual charges are also doubled, what would happen to the force between them?

Example6. A particle of mass m carrying charge ‘+q1‘ is revolving around a fixed charge ‘–q2‘ in a circular path of radius r. Calculate the period of revolution.

Example7. The force of repulsion between two point charges is F, when these are at a distance of 1 m. Now the point charges are replaced by spheres of radii 25 cm having the charge same as that of point charges. The distance between their centres is 1 m, then compare the force of repulsion in two cases.

Solutions:-

Coulomb's law numericals 