64. In the root-locus for open-loop transfer function K(s + 6) G(s) H(s) = (s + 3) (s + 5) the 'break away' and 'break-in', points are located respectively at

A. ?2 and 1

B. ?2.47 and ?3.77

C. ?4.27 and ?7.23

D. ?7.73 and ?4.27

65. If the open-loop transfer function of the system is G(s) H(s) ?s(s + 8) (s + 16) (s + 72) then a closed loop pole will be located at s = ?12, when the value of K is

A.4355

B.5760

C.9600

D.9862

66. An electromechanical device which accurates a train of step angular movements is response to a train of input pulses on one to one basis is

A. synchro control transformer

B. LVDT

C. stepper motor

D. ac tachogenerator

67. For a two-phase servo motor which one of the following statements is not true?

A. The rotor diameter is small

B. The totor resistance is low

C. The applied voltage are seldom balanced

D. The torque speed characteristics are linear.

68. Which one of the following transducers is used to obtain the output position in a position control system?

A. Strain Gauge

B. Lead cell

C. Synchro

D. Thermistor.

69. Consider the following statements regarding the number of sign changes in the first column of the Routh table in respect of the characteristic equation s2 + 2as + 4. TE a = + E, where E = near zero, the number of sign changes will be equal to zero. 2. If-a = 0, the number of sign changes will be equal to I. 3. If a = 1 E, where E = near zero, the number of sign changes will be equal to 2 Of these statements

A. 1, 2 and 3-are correct.

B. 1 and 2 are correct

C. 2 and 3 are correct

D. 1 and 3 are correct

70. Consider the following expressions which indicate the step or impulse response of an intially relaxed control system : 1. (5 ? 4e-2t) u (t) 2. (e-2t + 5) u (t) 3. 8(t) + 8e-2t u (t) 4. 8(t) + 4e-2t u(t) Those which correspond to the step and impulse response of the same system include

A. 1 and 3

B. 1 and 3

C. 2 and 3

D. 2 and 4

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