Reducing the mutual inductance linking a double tuned circuit causes the resonance curve peak to ___________________?
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Answer: C. Is raised
Explanation
Reducing mutual inductance between coupled coils decreases the magnetic coupling coefficient below the critical coupling threshold. As magnetic coupling drops below critical value, the double-tuned resonance curve loses its flat top and twin peaks. This reduction in coupling causes the frequency response curve to merge into a single higher and sharper peak. Double tuned circuits use magnetically coupled coils to achieve wide passbands with flat tops in radio receivers. Critical coupling produces the maximum possible flat-topped bandwidth without introducing an undesirable dip in the center. Under-coupling reduces the peak amplitude transfer while simultaneously sharpening the overall frequency selectivity response.
Stating that the resonance curve peak remains the same ignores the direct effect of changing mutual inductance. Lowering the peak contradicts the mathematical and physical behavior of under-coupled double-tuned resonant circuits. Selecting none of the above is wrong because the curve is indeed raised and sharpened as coupling decreases.
- Subject
- Engineering
- Category
- Electrical Engineering
- Topic
- —
- Difficulty
- medium
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