DC Motor-Generator I is a table top exhibit consisting of two identical DC permanent magnet motors with their outputs wired together. Meters and a switch-lamp are also wired to the outputs. When the visitor turns the armature of one motor, the other motor’s armature turns at the same rate. One motor has become a generator! The same is true if the visitor turns the second motor’s armature: it now becomes the generator. If the lamp is switched on, the motor spins more slowly, as some of the generator’s energy goes toward lighting the lamp.