Answer:

Given:
Two similar spheres having q and q charge kept certain distance force acts between the two.

To find:
If the middle of two spheres another similar q charge is kept experiences force magnitude and direction?

Solution:
When two similar spheres having q and q charge kept at a certain distance, the force acts between them is given by Coulomb's law:

F = kq^2/d^2

Where, k = 1/4πε0 is the Coulomb constant, ε0 is the permittivity of free space, and d is the distance between two charges.

Force between two spheres:
When two similar spheres having q and q charge kept at a certain distance, then the force between them is given by Coulomb's law.

F = kq^2/d^2

Force between middle charge and spheres:
When another similar q charge is kept at the middle of two spheres, then the force experienced by charge due to these two spheres can be calculated as follows:

Let's assume the distance between the middle charge and each sphere be r. Then the force experienced by the middle charge due to the first sphere is given by Coulomb's law as:

F1 = kq^2/r^2

Similarly, the force experienced by the middle charge due to the second sphere is given by Coulomb's law as:

F2 = kq^2/r^2

So, the net force experienced by the middle charge due to both the spheres can be calculated as:

F = F1 + F2

F = kq^2/r^2 + kq^2/r^2

F = 2kq^2/r^2

The direction of the force experienced by the middle charge will be attractive if the charge on the middle charge is opposite to the charges on the spheres. Otherwise, it will be repulsive.

Conclusion:
Thus, the force experienced by the middle charge due to two similar spheres having q and q charge kept at a certain distance is given by 2kq^2/d^2, and the direction of the force will be attractive or repulsive depending on the charge on the middle charge.

The middle charge will feel a force toward -q because -q attracts the test charge while +q repels it.the magnitude will be 2×4Kqq/d(square).