Which of the following statements about inductive reactance is true?

• A. XL is independent of frequency.
• B. XL increases with frequency.
• C. XL decreases with inductance.
• D. XL is determined by resistance.

Answer: (B)

Inductive reactance grows as the frequency of the AC signal increases. This happens because the opposition an inductor presents to a changing current is proportional to how fast the current is changing, and the standard relation is X_L = ωL = 2πfL. With a fixed inductance, doubling the frequency doubles the reactance, so XL rises with frequency. That’s why this statement is true. The idea that XL is independent of frequency is incorrect, since the formula shows a direct dependence on f. XL cannot decrease just by increasing inductance; in fact, increasing L raises XL because XL is proportional to L as well. And XL is not determined by resistance; resistance is a separate real part of impedance, while XL is the reactive (imaginary) part arising from inductance and frequency. For a quick check, an inductor of 0.1 H at 60 Hz has XL ≈ 37.7 Ω, and at 120 Hz it’s ≈ 75.4 Ω, illustrating the linear increase with frequency.