Question
What happens when an inductor is operated above its self-resonant frequency?
Answer Options
- A) Its reactance increases
- B) Harmonics are generated
- C) It becomes capacitive
- D) Catastrophic failure is likely
Correct Answer: C
Explanation
All physical inductors have some inherent, unavoidable shunt capacitance due to the close spacing of the wire windings. The inductor’s self-resonant frequency (SRF) is the point where the inductor’s own inductive reactance (X_L) equals and cancels its parasitic capacitive reactance (X_C).
Above the SRF, the parasitic capacitive reactance becomes the dominant factor, meaning the component behaves like a capacitor rather than an inductor. Consequently, it becomes capacitive (or appears as a capacitive reactance to the circuit), which can be disastrous for a circuit designed to operate with an inductive component.
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