An a.c. circuit contains \( 4\,\Omega \) resistance wire in series with an inductance coil of reactance \( 3\,\Omega \). The impedance of the circuit is :
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → \( 5\,\Omega \)
In a series LR circuit the voltage across the inductor leads that across the resistor by \( 90^\circ \), so the resistance and reactance add as perpendicular phasors, not directly. The impedance is
\( \displaystyle Z = \sqrt{R^{2} + X_L^{2}} = \sqrt{4^{2} + 3^{2}} = \sqrt{25} = 5\,\Omega \)