I have a question. I set up a voltmeter and and ammeter (properly connected in parallel and in series respectively) so that when I input power into a motor in the form of DC current, both the voltmeter and the ammeter read positive values. Then, I removed the voltage source (i.e. battery). Now what I don't understand is, if I manually rotate the motor in one direction, the motor (acting as a generator), I get a positive voltage reading and a negative current reading. If I rotate the motor (generator) in the other direction, I get a negative voltage reading and a positive current reading. I don't understand, how can current flow against the voltage established by the generator? Can someone please explain this phenomenon to me? Thanks.