This question is a regular feature in IoT interview questions for freshers, be ready to tackle it. Changing the voltage of the power source directly in the circuit is not straightforward. Pulse Width Modulation is an option in this scenario (PWM). Altering the rate at which electricity is given, also known as pulse width modulation or PWM, or pulse duration modulation (PDM). Using pulse width modulation (PWM), which is a method for creating an analogue signal from a digital source, it is possible to precisely regulate the amount of power supplied to a load with little loss. Since PWM modulates voltage, it may be used to adjust the output of a smart lighting system as well as the rotational speed of a motor.