Electric Potential of Only One Charge
The electric potential of only one charge is given by:
,
where R is the distance between the charge q and the point where we measure our voltage. So the only thing that has an influence on voltage is the distance R. The bigger R becomes, the smaller will V be.
If we want to measure the voltage from point P1 to point P2, then the voltage can be determined by:
,where Rp1 is the distance from the charge q to P1, and Rp2 is the distance from q to P2.
From the equation below
we can conclude that the bigger the difference between Rp1 and Rp2 becomes, the greater become the voltage between them.