CBSE Class 10 Answered

Electric potential at a point in an Electric field (for instance, let's take it as uniform) is the amount of work done in moving a unit positive charge from infinity to that point against electric forces. (attraction or repulsion)

whereas Electric potential difference between two points in an Electric field is defined as the amount of work done in moving unit positive charge from one point to another point against the electric force.

In other words, Potential difference is simply the difference of scalar potentials between two points or anything you consider...

Now let's take an example.

Say, you're placing a charge (+q) at the point O. Also, There are two points A & B in the electric field E(It acts outward since the line charge is positive). Now, you want to move a charge (say +q) from B to A. Then, you've to do some work against the force of repulsion. This work done is the potential difference between two points or Voltage (i.e.) WB?A=dV which further equals ?E.dx. Electric field is simply the force experienced by unit positive charge.

If you bring the same charge from ? instead of B, it's electric potential. Using the above figure & integrating for total work done (with limits ? to some scalar distance r), one could derive Electric potential at a point. It's given by V=q4??r. But, you could ask, "Why this work is not stored as some potential energy?"

Yes, It is. But, Potential energy requires the magnitude of another charge also... If r is the distance of separation of two charges, P.E. is given by Ep=qQ4??r. In other words, Ep=VQ