Automatic Control Systems - Section 1 (5)

Directions to Solve

33.

For the given figure C(s)/R(s)

13-47

Answer: Option A

Explanation:

41-47

34.

When a unit step voltage drives a lag network the output

A.	remains constant at unit step value
B.	increases exponentially from zero to final value
C.	decreases exponentially from 1 to 0
D.	either (b) of (c) depending on values of R and C

Answer: Option B

Explanation:

At t = 0 the capacitor behaves as a short-circuit and output voltage is 0. At t = ∞ capacitor behaves as an open-circuit and V0 = Vi.

35.

First column elements of Routh's tabulation are 3, 5, 28-268 It means that there

A.	is one root in left half s plane
B.	are two roots in left half s plane
C.	are two roots in right half s plane
D.	is one root in right half s plane

Answer: Option C

Explanation:

Since there are two sign changes in the first column, hence two roots in right half plane.

36.

From the noise point of view, bandwidth should

A.	be large
B.	not be too large
C.	should be as large as possible
D.	should be infinite

Answer: Option B

Explanation:

If noise is to be eliminated, bandwidth cannot be large.

37.

In the given figure, the input frequency is such that R = XC. Then

32-346

Answer: Option A

Explanation:

R = XC, voltage drops across R and XC are equal and at 90° with respect by each other. V0 lags Vi by 45°.

38.

In a two phase ac servomotor rotor resistance is R and rotor reactance is X. The speed curve will be linear if

Answer: Option A

Explanation:

In a two phase servomotor 42-198 ∠ < 1 so that torque speed curve is almost linear.

39.

A stepper motor is

A.	a two phase induction motor
B.	is a kind of rotating amplifier
C.	is an electromagnetic transducer used to convert an angular position of shaft into electrical signal
D.	is an electromechanical device which actuates a train of step angular movements in response to a train of input pulses on one to one basis