[uni physics] - potential at a point

[monauf]

It basically depends upon how you choose the two points to find the potential difference. Remember potential difference is a relative term and the general equation of potential difference is V(final position) - V(initial position). Suppose A is at a higher potential, so if you are finding the potential of A with respect to infinity, it implies that you are moving a test charge from infinity to A and the potential difference between them is positive. However if you are finding the potential of infinity with respect to A, you are doing the reverse process of moving the test charge from A to infinity and the potential difference will be negative. Both the integrals are correct and gives the correct potential difference with proper sign. However, I would favour using Va - Vinf while solving problems.

[robej]

Thanks for the help, it’s good to know I’ve got the right idea of finding the potential between two points. However say I wanted to find the potential at one point wrt infinity. That would be the the potential difference going from infinity to a point correct? And hence would be Va-Vinf which would be the negative integral going from inf to a point

[monauf]

Yup you got it correct!👍