274.  The loop gain GH of a closed loop system is given by the following expression s(s + 2) (s + 4) The value of K for which the system just becomes unstable is
A. K = 6
B. K = 8
C. K = 48
D. K = 96

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275.  For a given stepper motor, the following torque has the highest numerical value.
A. Detent torque
B. Pull-in torque
C. Pull-out torque
D. Holding torque

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276.  The following motor definitely has a permanent magnet rotor
A. DC commutator motor
B. Brushless dc motor
C. Stepper motor
D. Reluctance motor

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277.  For a tachometer if 0(t) is the rotor displacement is radians, e(t) is the output voltage and Kt is the tachometer constant in V/rad/sec, then the transfer E(s)function, will be 0(s)K,
A. Kts2
B.
C. Ks
D. Kt

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278.  A unity feedback system, having an open loop gain G(s) H(s) - K(1 - s) , becomes (1 + s) stable when
A. IKI > 1
B. K > 1
C. IKI < 1
D. K < -1

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279.  In the GH(s) plane, the Nyquist plot of the loop transfer function G(s)H(s) passes through the negative real axis at the point
A. (-0.25, j0)
B. (-0.5, j0)
C. (-1, j0)
D. (-2, j0)

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280.  The response of a system by -T + i =v. dtli the excitation is v = ke2t, then the forced response of i for t> 0 will be HAS 20001 k,
A. ?3 e'
B. 5? e-t
C. ?5 e-
D. ? sint + ?5 cost

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