Question

If we say that the electric potential of a point in space is 10 V, what do you understand from it? (Take potential at infinity as 0V)

• A. The amount of work done by external agent, in bringing a 10 C charge from infinity to that point (slowly) is 10J
• B. The amount of work done by external agent, in bringing a unit positive charge from infinity to that point (slowly) is 10 J
• C. The net magnitude of force acting on a unit positive charge at that point is 10 N
• D. The net work done to being a unit positive chargefrom infinity to that point (slowly) is 10 J

Answer 1

The correct option is B The amount of work done by external agent, in bringing a unit positive charge from infinity to that point (slowly) is 10 J

The potential of a point is defined as the work done to bring a Unit positive charge from infinity(which we usually take as zero potential) to that point. If some other point is taken as your 0V reference, then it’s the work done to bring a unit positive charge from that reference point to the given point.

Here, since the potential is given to be 10V, the work done is 10J on a unit positive charge.

[By the way, what is the importance of bringing the charge without accelerating it? Well there are several things at work here. Accelerating any object means doing extra work to add kinetic energy. And when a charge accelerates, it radiates energy, which you will learn about later. So all these phenomena add to the work done which is not part of the potential at a point.]