FCC Exam Question: 6A223

A "choke" coil:

A. Offers a relatively high impedance to AC currents
B. Has a high "Q" (low RF losses)
C. Offers a low resistance to DC currents
D. All of the above
Correct Answer: D

Explanation: A choke coil is an inductor specifically designed to impede or block alternating currents (AC) while allowing direct currents (DC) to pass with minimal opposition. A) **Offers a relatively high impedance to AC currents:** This is the primary function of a choke. An inductor's impedance ($X_L = 2\pi f L$) increases with both inductance (L) and frequency (f), effectively "choking" off AC signals. C) **Offers a low resistance to DC currents:** An ideal inductor has zero DC resistance. In practice, a choke coil is made of wire, giving it some inherent resistance. However, it's designed to have very low DC resistance to minimize voltage drop and power loss when DC current flows through it. B) **Has a high "Q" (low RF losses):** The "Q" factor (quality factor) indicates how efficiently an inductor stores energy versus dissipating it. A high Q means low resistive losses, which is desirable for a choke to perform effectively without wasting energy or overheating, especially in RF applications. Since a choke coil exhibits all these characteristics, D) All of the above, is the correct answer.

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Includes Elements 1, 3, 6, 7R, 8, and 9.