# What does it mean when two point charges form a dipole a small distance away from each other?

##### 1 Answer

Small, meaning close enough together.

Two charges can only interact well enough to form a dipole if they are close enough together. Too far apart and they are *essentially* independent charges (does ** not** mean they aren't interacting).

Consider the coulombic interaction between two point charges:

#V(vecr) = (q_1 q_2)/(4piepsilon_0vecr_(12)# where

#q_i# is the charge of particle#i# ,#epsilon_0 = 8.854 xx 10^(-12) "F"cdot"m"^(-1)# is the vacuum permittivity constant, and#vecr_(12)# is the radial separation between two particles.

This means the coulombic potential of the two charges depends on the distance between them and the charges' magnitudes. Large

#vecmu_(12) = qcdotvecr_(12)#

An example of a small charge is

An example of "small" for molecules is a few