1. The problem statement, all variables and given/known data The graph in the figure shows the electric field strength (not the field lines) as a function of distance from the center for a pair of concentric uniformly charged spheres. Which of the following situations could the graph plausibly represent? (There may be more than one correct choice.) A positively charged nonconducting thin-walled spherical shell inside of a positively charged conducting sphere. A positively charged conducting sphere within another positively charged conducting sphere. 2. Relevant equations 3. The attempt at a solution Alright, so I know that the above two are the only plausible situations, but I'm just trying to understand exactly why. For the second one, I think I understand. The electric field inside a conductor is 0, and outside, it falls off as 1/r^2. The start of the curve along 0 depicts the inside of the conductor, where the negative slope is depicting the space outside of the sphere before it reaches the walls of the sphere containing it? I'm a little confused there...(I hope I'm making some sense at least!) For the first instance, I'm really confused. I honestly don't know how to conceptualize that one at all. Any help would be great! Thanks!