Calculate the electric potential due to a charged ring

Here are two ways to calculate the electric potential difference (with respect to infinity) for a charged ring with a radius R and total charge Q. In the end, I make a slight error with the sign - but everything else seems ok.

[nyjahhaslam]

The negative sign that you dropped was when you integrate 1/2u^(3/2) it should be -1/u^(1/2). Thanks heaps for the video, much appreciated man!

[aagamjain]

The problem was that you didnt put negative sign in integration of u-³½

[jferro]

also, why didnt we change dq to (lambda)*R*d(theta) and then integrate from 0 to 2pi, in method 1?

[jferro]

i keep seeing the phrase " with respect to infinity" everywhere, and im not really sure i understand what it means. could you explain it a bit more? does it mean we are at an arbitrary point infinitely away directly on the z axis?

[candoga]

I think it's better you to stop making jokes :) But thanks for the nice explanation though :)