A single voltage pulse can cause a DC motor to advance slightly, but the relationship between pulse characteristics and motor movement is complex due to inductive lag. Changing the amplitude or width of the pulse affects the power delivered to the motor, but does not guarantee a straightforward increase in speed or movement. For stepper motors, speed is determined by the frequency and number of pulses sent to the motor. AC motors can achieve increased speed through variable frequency drives (VFDs), which utilize pulse width modulation (PWM) to control speed. Understanding the specific motor type and its specifications is crucial for optimizing performance.