How do varactors tune the frequency in voltage-controlled oscillators (VCOs)?

To calculate active power in an AC circuit, you need to know the voltage (V) and the current (I) flowing through the circuit. The formula for calculating active power is:

Active Power (P) = Voltage (V) × Current (I) × Power Factor (PF)

Where:

Voltage (V) is the RMS (Root Mean Square) voltage in volts (V).

Current (I) is the RMS current in amperes (A).

Power Factor (PF) is a dimensionless value between 0 and 1 that represents the phase relationship between voltage and current. It indicates the efficiency of the circuit in converting electrical power into useful work.

In many cases, the power factor is not explicitly given, but it can be determined if you know the type of load in the circuit. Common power factors for various loads are:

Resistive loads (e.g., incandescent bulbs, heating elements): Power factor = 1 (unity)

Inductive loads (e.g., motors, transformers, solenoids): Power factor < 1 (lagging power factor)

Capacitive loads (e.g., some power factor correction systems): Power factor < 1 (leading power factor)

If the power factor is not given, and you are working with a resistive load, you can assume a power factor of 1 for simplicity.

Keep in mind that if you are working with AC waveforms, both voltage and current must be expressed in RMS values to get accurate results for active power calculation.