What is the formula for inductive reactance (Xl)?

• A. Xl = 2πfL
• B. Xl = R + X
• C. Xl = 1/(2πfC)
• D. Xl = V/I

Answer: (A)

The formula for inductive reactance (Xl) is derived from the relationship between inductance, frequency, and the properties of alternating current (AC) circuits. The correct formula, Xl = 2πfL, indicates that inductive reactance increases with both the frequency of the alternating current (f) and the inductance (L) of the coil or inductor.

In this formula, 2π is a constant that arises from the conversion of frequency from hertz to radians per second (since one complete cycle corresponds to 2π radians). The term 'f' represents the frequency in hertz (Hz), which reflects how often the alternating current changes direction in one second, while 'L' is the inductance measured in henrys (H), a unit that describes how much magnetic field is generated by the inductor for a given current.

When you multiply these components together, you find the inductive reactance, which quantifies how much the inductor resists the change in current due to its ability to store energy in a magnetic field. As frequency or inductance increases, so does the reactance, indicating greater opposition to the flow of current.

Understanding this relationship is crucial for analyzing AC circuits and their behavior