JAMB Physics 2021 Paper

Concept:At resonance in a series R-L-C circuit, the inductive and capacitive reactances are equal.Explanation:At resonance, $X_L = X_C$.The same current flows through the inductor and the capacitor.Thus, $V_L = V_C$ because $V = IX$ and the currents are equal.Given that the voltage across the inductor is $40\,\text{V}$, the voltage across the capacitor must also be $40\,\text{V}$.The $30\,\text{V}$ across the resistor is not needed for this comparison.Answer:B. $40\,\text{V}$