In class, we made a coil of wire and used it to make a simple electric motor with a magnet. I put two square 9v batteries in series for a total of 18v to power the motor.
I then used a larger 12v battery ( probably about 2x4x4 inches ) to power it. The 12v caused the motor to spin a lot faster and even cause some arcing.
Why is this so? Why would a lower voltage cause the motor to spin faster? Does it have to do with internal resistance of the battery? What other factors are at play here?
Sorry, but I don't know the specific 12v battery, that's why I described it's dimensions. The "motor" was just hand made by coiling about 28 AWG wire a couple of times.