The IMPEDANCE of a series RL circuit at angular frequency $\omega$ is

1. Series impedances ADD: $Z_{RL} = Z_R + Z_L = R + j\omega L$. 2. Magnitude: $|Z| = \sqrt{R^2 + (\omega L)^2}$. 3. Phase: $\arctan(\omega L / R)$ — between 0° (pure R) and 90° (pure L) as $\omega L$ increases. 4. Option A is dimensionally wrong. Option B has wrong sign on $j\omega L$ (would be capacitive!). Option D has the capacitor formula. _Source: Tony Kuphaldt, "Lessons in Electric Circuits — AC", Vol II, Ch 5 (Series RLC impedance)._