What is meant by impedance?

What is meant by impedance?

• A. The total opposition to the flow of alternating current, and is the vector sum of resistance, capacitive reactance, and inductive reactance
• B. The rate of energy transfer in a circuit
• C. Voltage divided by current
• D. The product of resistance and reactance

Answer: (A)

Impedance is the total opposition to alternating current. It combines resistance, which dissipates energy and stays in phase with current, with reactance from capacitors and inductors, which is frequency-dependent and shifts the phase between voltage and current. Because these parts don’t all behave the same way in time, impedance isn’t just a single number but a complex quantity that is added as a vector: Z = R + j(XL − XC). The magnitude of impedance is |Z| = sqrt(R^2 + (XL − XC)^2), and it relates voltage and current through V = IZ. That description matches the statement that impedance is the total opposition to AC and is the vector (phasor) sum of resistance, capacitive reactance, and inductive reactance. The other ideas describe related but different concepts: energy transfer rate is power; voltage divided by current gives a magnitude that relates to impedance under specific conditions but doesn’t capture its phase and complex nature; and simply multiplying resistance and reactance isn’t how impedance is formed.

Impedance is the total opposition to alternating current. It combines resistance, which dissipates energy and stays in phase with current, with reactance from capacitors and inductors, which is frequency-dependent and shifts the phase between voltage and current. Because these parts don’t all behave the same way in time, impedance isn’t just a single number but a complex quantity that is added as a vector: Z = R + j(XL − XC). The magnitude of impedance is |Z| = sqrt(R^2 + (XL − XC)^2), and it relates voltage and current through V = IZ.

That description matches the statement that impedance is the total opposition to AC and is the vector (phasor) sum of resistance, capacitive reactance, and inductive reactance. The other ideas describe related but different concepts: energy transfer rate is power; voltage divided by current gives a magnitude that relates to impedance under specific conditions but doesn’t capture its phase and complex nature; and simply multiplying resistance and reactance isn’t how impedance is formed.