Suppose a strength that acts between two charges depends on the distance, 1/r^a, where
What will happen with a punctual charge, if it is put within a uniformly charged sphere. At the initial moment the punctual charge is in rest.
F is proportional to 1/r^a.
The Attempt at a Solution
The solution says that for a> 2 the punctual charge q goes toward point O, that it is the center of the sphere, in case of same signals.
and for a<2 the punctual charge goes toward point B that is in the surface of the sphere.
And if the signals are opposite it happens the opposite too.
I don't understand this. Why of going toward the center and the surface of the sphere?