Electrical Engineering ⇒ Topic : Electric Potential

Electric Potential

Just as we define electric field intensity as the force per unit charge, similarly electric potential is defined as the electric potential energy per unit charge.

                                                               figure (a)

Consider an isolated charge +Q fixed in space as shown in Fig. (A). If a unit positive  charge (i. e. + 1C) is placed at infinity, the force charge on it due to charge +Q is *zero. If the unit positive charge at infinity is moved towards +Q, a force of repulsion acts on it (like charges repel) and hence work is required to be done to bring it to a point like A. Hence when the unit positive charge is at A, it has some amount of electric potential energy which is a measure of electric potential. The closer the point to the charge, the higher will be the electric potential energy and hence the electric potential at that point. Therefore,electric potential at a point due to a charge depends upon the position of the point; being zero if the point is situated at infinity Obviously, in electric field, infinity is chosen as the point of **zero potential.

Hence electric potential at a point in an electric field is the amount of work done in bringing a unit positive charge (i.e. +1 C)from infinity to that point i.e.

Unit. The SI unit of electric potential is *volt and may be defined as under :The electric potential at a point in an electric field is 1 volt if 1 joule of work is done in bringing a unit positive charge (i.e. +1 C)from infinity to that point **against the electric field Thus when we say that potential at a point in an electric field is +5V, it simply means that 5 joules of work has been done in bringing a unit positive charge from infinity to that point