Difference Between Electric Potential and Potential Difference is also related topic to the electrostatics.
Electric potential at a point in an electric
field is equal to the amount of work done in bringing a unit
positive charge from infinity to that point.
If W is the work done in moving a unit positive charge from
infinity to a certain point in the field, the electric potential V
at this point would be given by
V=W/Q ………. (13.6)
It implies that electric potential is measured relative to some
reference point and like potential energy we can measure
only the change in potential between two points.
Electric potential is a scalar quantity.
Its SI unit is volt which is equal to J C-1.
If one joule of work is done against the electric field in
bringing one coulomb positive charge from infinity to a point
in the electric field then the potential at that point will be one
volt. Or if the potential energy of one coulomb of charge at a
point in the electric field is one joule, the potential of that
point will be one volt.
A body in gravitational field always tends to move from a
point of higher potential energy to a point of lower potential
energy. Similarly, when a charge is released in an electric
field, it moves from a point of higher potential say A to a point
at lower potential say B (Fig.13.16). If the potential of point A
is Va and that of point B is Vb, the potential energy of the
charge at these points will be qVa and qVb respectively. The
change in potential energy of the charge when it moves from
point A to B will be equal to qVa– qVb. This energy is utilized in
doing some useful work. Thus
Energy supplied by the charge = q (Va– Vb) ………. (13.7)
If q is equal to one unit, then the potential difference
between two points becomes equal to the energy supplied
by the charge. Thus, we define potential difference between
two points as the energy supplied by a unit charge as it moves
from one point to the other in the direction of the field.
If a positive charge is transferred from a point of lower
potential to a point of higher potential i.e. against the field
direction, energy would have to be supplied to it.
When we release a negative charge in an electric field, its
behaviour will be opposite to that of positive charge. A more
useful unit for the electrical energy is electron volt (eV).
Where VA and VB are defined electric potentials at points A and B respectively.Electric potential energy difference and electric potential difference between the points A and B are related as
Thus the p.d between the two points can be defined as “the difference of the potential energy per unit charge.”
That is,a potential difference of 1 volt exists between two points if work done in moving a unit positive charge from one point to other ,keeping equilibrium,is one joule. In order to give a concept of electric potential at a point in an electric field,we must have a reference to which we assign zero electric potential.this point is usually taken at infinity .Thus in equation
we take A to be at infinity and choose Va=0,the electric potential at B will be
or dropping the subscripts we have an equation
which states that the electric potential at any point in an electric field is equal to work done in bringing a unit positively charge from infinity to that point keeping it in equilibrium.It is to be noted that potential at a point is still potential difference between the potential at that point and potential at infinity.Both potential and potential differences are scalar quantities because both W and q0 are scalars. Watch video about electric potential and potential difference to clear your concepts visually.
Video about Difference between electric potential and potential difference
To see the difference between electric potential and potential difference watch video given below: