Metal sphere A has a charge of −. An identical metal sphere B has a charge of +2. The magnitude of the electric force on sphere B due to sphere A is F. The magnitude of the electric force on A due to B must be:.

Force on Sphere A due to B = F

Explanation:

The electrostatic force between the two charges is given by the Coulomb's Law, by the following formula:

F₁₂ = kq₁q₂/r²

where,

F₁₂ = Force on charge 1 due to charge 2

k = Coulomb's Constant

q₁ = magnitude of charge 1

q₂ = magnitude of charge 2

r = distance between both the charges

Similarly, the force on charge 2 due to charge 1 is given by the following formula:

F₂₁ = kq₁q₂/r²

It is clear from the formula that the force of both the charges on each other due to the other charge are same. Therefore, in our case:

Force on Sphere A due to B = Force on Sphere B due to A

Force on Sphere A due to B = F