What is the force between two small charged spheres having charges of 2 × 10^–7 C and 3 × 10^–7C placed 30 cm apart in air?

The formula used to find the force, F is given as,

…(1)

Where, q₁ and q₂ are the charges.

r is the distance between the charges.

is a constant and its value is 9x10⁹ N m² C^-2

ϵ₀ is the permittivity of free space. Its value is 8.85 x 10^-12 (F/m)

Now, the diagram is:

Since, both the charges are positive, thus, the nature of force will be repulsive. F₁₂ is the force on charge q₁ caused by charge q_2.

Now, Given:

Charge on the first sphere, q₁ = 2 × 10^–7 C

Charge on the second sphere, q₂ = 3 × 10^–7 C

Distance between the spheres, r = 30 cm = 0.3 m

Putting the values in equation (1), we get,

F = 6 × 10^-3 N

Hence, the force between the given charged particles will be 6 × 10^-3 N. Since the nature of the charges is the same i.e. they are both positive. Hence, the force will be repulsive.