What does impedance (Z) calculate using the formula Z = √R2 + X2?

• A. Power
• B. Current
• C. Voltage
• D. Resistance

Answer: (D)

Impedance (Z) is a comprehensive measurement in AC circuits that takes into account not only the resistance (R) but also the reactance (X). The formula ( Z = \sqrt{R^2 + X^2} ) clearly indicates that impedance is derived from the vector sum of resistance and reactance.

In this context, resistance is a component of impedance, representing the opposition to current flow that results in the dissipation of energy in the form of heat. Reactance, on the other hand, represents the opposition to current flow due to inductors and capacitors, which does not dissipate energy but stores it temporarily. By calculating impedance using this formula, one can understand the total opposition offered by an electrical component or circuit when subjected to alternating current (AC).

The other choices refer to different electrical parameters. Power relates to the rate at which electrical energy is transferred, current is the flow of electric charge, and voltage is the potential difference that drives the current. None of these are calculated using the described formula for impedance, reinforcing that the correct answer specifically defines what impedance calculates through its relationship with resistance.