Q$4$: Two tiny conducting spheres are identical and carry charges of $-20\mathrm{.}0C$ and $+50\mathrm{.}0C.$ They are separated by a distance of $2\mathrm{.}50cm.($a$)$ What is the magnitude of the force that each sphere experiences, and is the force attractive or repulsive? $($b$)$ The spheres are brought into contact and then separated to a distance of $2\mathrm{.}50cm.$ Determine the magnitude of the force that each sphere now experiences, and state whether the force is attractive or repulsive.