You have an uncharged sphere of unknown material and you would like to determine if the material is an electrical conductor or insulator. You devise and perform the following experiment:
First, you touch the sphere with a negatively charged rod so that charge is transferred to the sphere as shown in figure a. Then, you bring a similarly charged rod, suspended from a string near (not touching) the sphere. The rod is repelled by the sphere.
Based off this experiment, is the sphere an insulator or a conductor? Choose the best explanation for why.