Which term is the measure of the total opposition to current flow in an alternating-current circuit?

• A. Galvanic Corrosion
• B. Impedance
• C. Lead-Free Frit
• D. Lite

Answer: (B)

Total opposition to current flow in an alternating-current circuit is called impedance. In AC, components don’t just resist current; they can also oppose it through inductive and capacitive effects. Impedance brings all of that together into one quantity that has a size (how much it resists) and a phase (how much the current lags or leads the voltage).

Think of resistance as a plain opposition to current, while inductive reactance (from coils) and capacitive reactance (from capacitors) change with frequency and affect the timing between voltage and current. Impedance combines these factors into Z, a complex quantity whose magnitude tells you the overall opposition (in ohms) and whose angle tells you the phase relationship. For a circuit with resistance R, inductance L, and capacitance C at a given frequency (with ω = 2πf), the magnitude is |Z| = sqrt(R^2 + (ωL − 1/(ωC))^2). A larger impedance means less current for the same applied voltage.

The other terms don’t describe this electrical concept: galvanic corrosion is a chemical process, lead-free frit is a ceramic glaze material, and lite isn’t a technical term for electrical impedance.