Calculate the potential of a point charge Q1 sitting in the coordination origin as a function of the distance r. Assume that for r = ∞

ϕ (r) = 0. What energy do you have to expend to transfer the charge Q2 beetwen any two points (A,B) from the charge Q1.

So what I've tried is this;

ϕ (r) = \[ -\int_0^r E * ds \]

Now here I am missing the E so I've found this formula

\[ E = \frac{1}{4 * \pi * e0} * \frac{Q} {r^2} \]

So I've still got the same issue. What is my r and what is my Q. Should I put Q as e = 1,6?

Does the fact that it is sitting in the spot 0,0 mean anything. Also r is confusing me, r should be the distance,between the two points. Now I havent found anywhere how to calculate this distance.

Some guidance would be great, thanks!