CBSE Class 10 Answered

Because it's the difference between two potentials which exists at two different points.

A potential at a point in electric field is the potential energy of the charge configurations divided by the test charge.

Let's consider a horizontal charged sheet of uniform positive charge density.

Let's hang two very tiny balls with a tiny positive charge on each. The charge on both of them is same. But there distance from the sheet be y and 2y repectively.

They'll be repelled away from the charged sheet due to positive charge, but will be held in position due to gravity.

In there equilibrium positions they have a potential energy assocaited. And each potential energy is different, since they are hanging by silk thread, against the force of gravity and electrostatic.

The potentials at the locations of these two balls is their electrostatic potential energy/charge on them.

As we can see these potentials are different.

If we take the difference of two potentials we are talking about the potential difference between these two points.

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