Electronics and Communication Engineering - Automatic Control Systems

41. 

Assertion (A): Positive feedback is not used in any circuit.

Reason (R): Positive feedback leads to instability.

A. Both A and R are correct and R is correct explanation of A
B. Both A and R are correct but R is not correct explanation of A
C. A is correct but R is wrong
D. R is correct but A is wrong

Answer: Option D

Explanation:

Positive feedback is used in oscillator circuits.


42. 

For the equation where Q is heat energy Gt is thermal conductance and θ is temperature, analogous electrical equation is

A. i = G(v1 - v2)
B.
C.
D.

Answer: Option A

Explanation:

Temperatures θ1 and θ2 are analogous to voltage v1 and v2 .


43. 

If the Nyquist plot does not encircle the (-1 + j0) point the system is always stable.

A. True
B. False

Answer: Option B

Explanation:

It is not necessary.


44. 

In op-amp circuit of the given figure, Eo(s)/Ei(s) =

A.
B.
C.
D.

Answer: Option A

Explanation:


45. 

A system hasFor unit step input the settling time for 2% tolerance band is

A. 1.6
B. 2.5
C. 4
D. 5

Answer: Option D

Explanation:

ξωn - 0.8 and = 1.25 s. For 2% criterion, settling time = 4T = 5 seconds.