The

absolute potential at a point is the work done against

electric forces in carrying a unit positive test-charge from

infinity to that point. Hnece the absolute potential at a point

**B** is the difference in potential from

**A = ∞** to

**B**.

Consider a point charge **q** in vacuum and a point **P** at a distance **r** from the point charge. The absolute potential at **P** due to the charge **q** is:

**V** = k · q / r

where **k = 8.99 · 10**^{9}^{2} / C^{2} is the Coulomb constant. The absolute potential at infinity (at r = ∞) is zero.

Becuase of the superposition principle and the scalar nature of potential difference, the absolute potential at a point due to a number of point charges is:

**V** = k · Σ q_{i} / r_{i}

where the r_{i} are the distances of the charges q_{i} from the point in question. Negative **q**'s contribuet negative terms to the potential, while positive **q**'s contribute positive terms.

The absolute potential due to a uniformly charged sphere, at points *outside* the sphere or *on* its surface is **V** = kq / r, where **q** is the charge on the sphere. THis potential is the same as that due to a point charge **q** placed at the position of the sphere's center.