Question

Why is it said that potential difference is the work done in bringing unit positive charge from 1 point to another, when positive charge is said to be intact i.e only electrons flow?

Answer 1

Positive charge is just a test charge. Potential difference between point A and point B is work needed to be done in moving the that test charge from A to B.

Compare it with gravity if you will. The potential energy difference between height A and height B is the work done is moving a mass of 1 kg from A to B. Why there is work needed at all? Because there are lines of forces already in form of gravity.

Similarly work is needed to be done in moving test charge because there is presence of lines of forces in form of Electric field.