**Multiple
Charges**

**Remember that potential difference (the voltage) is
basically a potential energy divided by a charge q. Therefore,
everything we did for the electric PE of charge q due to the
presence of several other charges Q is immediately applicable here
and now. **

**Since PE is a scalar, V is also a scalar.**

**With these charges already in place, what is the electric
potential at some point -- some region of space -- we might label
P?**

**Voltage, like PE, is a scalar, so we need only add the
potentials (or potential differences or voltages) due to each of
these charges. That is,**

**That's all there is to it!**

**However, let's continue with a numerical example.**

**What is the electric potential -- the voltage -- at point P? What is the
electric potential at point P because the charges Q's are there? **

**Find the potential at point P for each charge Q; then add up
the sum (ordinary, scalar addition).**

**Remember**, **voltage, like PE, is a scalar, so we need
only add the potentials (or potential differences or voltages) due to each
of these charges in an ordinary, common, scalar equation.**