The first law to be discovered on how charges can create fields was Coulomb’s law:
This equation gives us the field at position caused by a charge at .
is a constant of nature, the value of which we shall discuss a little later. The electric field caused by a group of charged objects is simply the vector sum of the electric fields caused by the individual charges. Note that on the right hand side the first term is the magnitude of the field times the sign (positive or negative) of the charge and the second term is a unit vector pointing away from the charge.