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If the loop gain K of a negative feedback system having a loop transfer function
K(s + 3) (s + 8)2
is to be adjusted to induce a sustained oscillation then
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The frequency of this oscillation must be 4 rad / s √3 - The frequency of this oscillation must be must be 4 rad/s
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The frequency of this oscillation must be must be 4 or 4 rad / s √3 - such a K does not exist
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Correct Option: D
Characteristic equation is
| 1 + | = 0 | |
| (s + 8)2 |
⇒ s2 + (16 + K) s + 3K + 64 = 0
Routh's array,
⇒ No such K exist to make all element of a row equal to 0.
