Electronics and Communication Engineering - Automatic Control Systems

21. 

In the given figure the input frequency is such that R << Xc, then

A. v0 lags vi by 90°
B. v0 leads vi by 90°
C. v0 and vi are in phase
D. either (b) or (c)

Answer: Option A

Explanation:

Voltage across capacitor lags by 90°.


22. 

In the given figure, of potentiometer V0 = Vi (R0/Ri) only when

A. RL = 0
B. RL = ∞
C. RL is neither low nor high
D. RL is low but not zero

Answer: Option B

Explanation:

If RL is not infinite, the voltage ratio of potentiometer depends on the value of RL. This is called loading effect.


23. 

A unity feedback system has open loop transfer function The closed loop transfer function is

A.
B.
C.
D.

Answer: Option B

Explanation:

.


24. 

Bellows converts

A. pressure difference into displacement
B. pressure difference into voltage
C. displacement into pressure difference
D. either (a) or (c)

Answer: Option A

Explanation:

To measure pressure, it is convenient to convert pressure into displacement and then use a displacement transducer.


25. 

Assertion (A): The steady state response, of a stable, linear, time invariant system, to sinusoidal input depends on initial conditions.

Reason (R): Frequency response, in steady state, is obtained by replacing s in the transfer function by jω

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:

Steady state response does not depend on initial conditions.