JAMB Physics 2019 Paper

Concept:In an a.c. circuit, power is absorbed only by resistance; inductance does not consume real power.Explanation:Current $I = 1\,\text{A}$ flows through the circuit.Resistance of the coil $R = 5\,\Omega$.Frequency $f = 800\,\text{Hz}$ does not affect the real power absorbed.Inductance $L = 2.5\,\text{mH}$ only stores and returns energy, so it does not contribute to power absorbed.Therefore, average power absorbed is given by $P = I^2 R$.Substitute values: $P = (1)^2 \times 5 = 5\,\text{W}$.Answer:$P = 5\,\text{W}$, so the correct option is A.