Apparent power in an AC circuit is calculated using the circuit impedance, which includes which components?

Apparent power in an AC circuit is calculated using the circuit impedance, which includes which components?

• A. Reactance and Resistance
• B. Capacitance and Inductance
• C. Voltage and Current
• D. Power and Energy

Answer: (A)

In AC circuits, apparent power comes from the overall opposition to current called impedance, which is made up of a resistive part and a reactive part. The resistive part, resistance, is in phase with voltage and represents real power dissipation. The reactive part, reactance, can be inductive or capacitive and shifts the current relative to the voltage, storing and returning energy each cycle. Impedance is written as Z = R + jX, where R is resistance and X is reactance. The magnitude of impedance is |Z| = sqrt(R^2 + X^2), and apparent power S equals the product of the RMS voltage and RMS current, S = V_rms I_rms. The phase angle between voltage and current is determined by X and R (tan(phi) = X/R), which is why both components matter for apparent power. Capacitance and inductance are specific sources of reactance, but the essential components of impedance are resistance and reactance.

In AC circuits, apparent power comes from the overall opposition to current called impedance, which is made up of a resistive part and a reactive part. The resistive part, resistance, is in phase with voltage and represents real power dissipation. The reactive part, reactance, can be inductive or capacitive and shifts the current relative to the voltage, storing and returning energy each cycle. Impedance is written as Z = R + jX, where R is resistance and X is reactance. The magnitude of impedance is |Z| = sqrt(R^2 + X^2), and apparent power S equals the product of the RMS voltage and RMS current, S = V_rms I_rms. The phase angle between voltage and current is determined by X and R (tan(phi) = X/R), which is why both components matter for apparent power. Capacitance and inductance are specific sources of reactance, but the essential components of impedance are resistance and reactance.