This grading rubric show an example of an acceptable answer, however I wonder if the slopes at the surface of the second sphere are wrong. This is a previous AP Physics test question so I'm inclined to trust the key, however, the graph is not presented as "the correct answer" but just as an "acceptable answer" and I want to dig deeper into it.

[![voltage graph of a conducting sphere in the presence of another charge](https://i.stack.imgur.com/VNFFT.png)](https://i.stack.imgur.com/VNFFT.png)

The sphere on the left is a conductor with a net charge; the sphere on the right is an uncharged conductor.

The graph shows "curved segment 1" between the two spheres ending with a slope of zero and "curved segment 2" to the right of the second sphere has a steep slope. It's almost like two separate 1/r graphs.

My thought was that it should look like a single 1/r graph with a flat "pause" in the middle that picks up with the same slope it left off with - that the slopes immediately to the left and right of the second sphere should both be shallow negative and match one another.

Which graph is correct and why?