A fixed frequency signal in which the percentage of ON time can be varied is known as:

A) sine wave
B) pulse width modulation
C) frequency modulation
D) 3-Phase AC

Pulse Width Modulation

A method used in electronic control to regulate the amount of power delivered to an electrical device, by effectively chopping up the power supply into controlled intervals.

Fixed Frequency

A characteristic of oscillating systems or signals that maintain a constant frequency over time, typically used in various electronics and communications systems.