Electric field (E) due to a point charge (Q) is:

E = k Q/d² …………………………………… (3-7)

Electric potential (V) due to a point charge is:

V = k Q/d ………………………………… (3-8)

Equation (3-5) can rewrite as:

W = q.V = q. k Q /d = k q Q/d ……......... (3-9)

The important facts for electrical potential:

1. The potential at infinity is zero.

2. The electric potential of positive charge is positive. When moving a charge from infinity to this point, the electric potential increases, and the electrical energy increased above a zero level.

3. The electric potential of a negative charge is negative. When moving a charge from infinity to this point, the electric potential decreases, and the electrical energy decreased below a zero level.

4. The relation between the electric field and electric potential is

(V = Ed), and units for electric field (N/C) can be written as V/m.