The electric potential at a point in an electric field is defined to be the work done to move a unit positive charge from infinity to that point. When the electric charge at infinite distance away from a point charge is defined to have a zero potential, when that charge is moved closer to the point charge, its potential increased. Therefore, the electric field for a point charge (Q) is:

Figure 1

E = k Q/d² ………………………………….. (3-1)

Where E = electric field

k = 1/4π ε₀ = 9.0 x 10⁹ N.m²/C²

d = distance

Electric potential = work done/charge moved

E = W/q ……………………………………… (3-2)

If work is measured in Joule (J), and charge in coulomb's (C), then potential is measured in volt (v):

1 volt = 1 Joule/1Coulomb ………………… (3-3)

Electric potential is a scalar quantity.

The electric field strength between two oppositely charged parallel plates is:

E = V/d ………………………………………. (3-4)

Where: E = electric field

V = potential between the plates

d = distance between the plates