Which term describes opposition to alternating current in a circuit?

Which term describes opposition to alternating current in a circuit?

• A. Impedance
• B. Resistance
• C. Reactance
• D. Conductance

Answer: (A)

Opposition to alternating current in a circuit is described by impedance. In AC, circuits include resistors, inductors, and capacitors, and impedance captures how all of these elements together oppose current. It has two parts: a real part, resistance, which dissipates power, and an imaginary part, reactance, which stores and returns energy. Reactance comes from changing current in inductors and capacitors and depends on frequency. The total opposition is represented as Z = R + jX, or in magnitude and phase form as |Z| and an angle, combining both effects. Conductance is the reciprocal of resistance and doesn’t describe the full opposition to AC. So impedance is the correct term.

Opposition to alternating current in a circuit is described by impedance. In AC, circuits include resistors, inductors, and capacitors, and impedance captures how all of these elements together oppose current. It has two parts: a real part, resistance, which dissipates power, and an imaginary part, reactance, which stores and returns energy. Reactance comes from changing current in inductors and capacitors and depends on frequency. The total opposition is represented as Z = R + jX, or in magnitude and phase form as |Z| and an angle, combining both effects. Conductance is the reciprocal of resistance and doesn’t describe the full opposition to AC. So impedance is the correct term.