Which terms are included in impedance for alternating current?

Which terms are included in impedance for alternating current?

• A. Resistance only
• B. Resistance and capacitance
• C. Resistance, capacitive reactance, and inductive reactance
• D. Inductive reactance only

Answer: (C)

Impedance in alternating current is the total opposition to current that combines the real power-dissipating part with the reactive effects from energy storage elements. The real part is resistance, which stays the same in AC and dissipates energy as heat. The reactive parts come from capacitors and inductors: capacitive reactance Xc = 1/(ωC) and inductive reactance XL = ωL. These reactances create phase shifts between voltage and current, with capacitors tending to make current lead voltage and inductors making current lag voltage. Together they form Z = R + j(XL − XC), so impedance includes resistance, capacitive reactance, and inductive reactance. Dropping any one of these would omit part of what opposes AC current, which is why the full trio is the correct description.

Impedance in alternating current is the total opposition to current that combines the real power-dissipating part with the reactive effects from energy storage elements. The real part is resistance, which stays the same in AC and dissipates energy as heat. The reactive parts come from capacitors and inductors: capacitive reactance Xc = 1/(ωC) and inductive reactance XL = ωL. These reactances create phase shifts between voltage and current, with capacitors tending to make current lead voltage and inductors making current lag voltage. Together they form Z = R + j(XL − XC), so impedance includes resistance, capacitive reactance, and inductive reactance. Dropping any one of these would omit part of what opposes AC current, which is why the full trio is the correct description.