# Is there a limit to the distance at which electric field can act?

Say you have a positive electric charge at point A in empty space. Across ten light years there is another positive charge at point B.

The charge at point B has forces on it from the charge at point A. If the charge at point A was changed to a negative one, does the direction of force on charge B change instantly? Additionally, is there any limit to the distance at which these forces can be produced?

According to the classical theory of electromagnetism, there is no limit. The force has an infinite range. This would not be true if the photon were not massless. There have been many experiments measuring the photon mass, and we can say with certainty it is less than $10^{-18}~eV/c^2$