Which of the following equations is correct for calculating the critical or cut-off frequency for the circuit in Figure 18-5?
A) Fc = 1/2n LR)
B) Fc = 1/[2n L/R)]
C) Fc = 1/[2n LR)]
D) Fc = 2nL/R)

Question

Quizplus · Accepted Answer

The correct formula for calculating the critical or cut-off frequency (Fc) of a circuit, particularly in contexts involving inductance (L) and resistance (R), is Fc = 1/[2π(L/R)]. This formula takes into account the inductive reactance and resistance in the circuit. Choice B, Fc = 1/[2π L/R)], closely represents this correct formula by incorporating the elements of inductance and resistance in the denominator, correctly positioned within the brackets to indicate division, and preceded by the factor 1/[2π], which is essential for calculating frequencies in such contexts. The correct formula accounts for the relationship between the inductance, resistance, and the frequency at which the impedance of the inductor equals the resistance, thus defining the cut-off frequency.

Which of the Following Equations Is Correct for Calculating the Critical