My circuit works perfectly fine, but i’m trying to understand what causes my motor to work. As you can see in the attachment provided the positive end of the motor is connected to the 9v battery, while the negative end is connected to the output signal from the transistor. My question is how exactly is the circuit closed? Does a change in voltage from ground, caused by the transistor allow the motor to draw power from the 9v battery? Thank you for your support.