FCC Exam Question: 6A80

If a turn in an inductor is shorted:

A. There will be an decrease of induction
B. There will be a decrease of Q
C. There will be overheating with possible burnout
D. All of the above
Correct Answer: D

Explanation: A shorted turn in an inductor fundamentally alters its behavior, leading to all the listed effects: * **Decrease of Inductance:** A shorted turn effectively bypasses a portion of the coil. The magnetic field generated by the current in the rest of the coil will induce a current in the shorted turn, which in turn creates a magnetic field that opposes the main field. This counteracting field reduces the overall effective inductance of the coil. * **Decrease of Q (Quality Factor):** Q is the ratio of an inductor's reactance to its resistance (X/R). A shorted turn acts as a low-resistance path where significant circulating currents can flow. These currents cause substantial resistive losses (I²R), increasing the total effective resistance of the inductor. With increased resistance, the Q-factor decreases significantly. * **Overheating with Possible Burnout:** The large circulating current induced in the shorted turn will generate considerable heat due to its inherent (even if small) resistance (P = I²R). This excessive heat can damage the wire's insulation or melt the conductor, leading to permanent failure or "burnout." Therefore, all these consequences are interconnected and result from the energy dissipation and change in magnetic coupling caused by a shorted turn.

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