Question 1

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

Accepted Answer

.

Question 2

For the circuit in the given figure, V2(s)/V1(s) =

Accepted Answer

.

Question 3

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

Accepted Answer

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

Question 4

For the control system in the given figure, the value of K for critical damping is

Accepted Answer

since ζ = 1, ωn = 3.5 Hence 2 + 2k = 3.52 = 12.25 or K = 5.125 .

Question 5

First column elements of Routh's tabulation are 3, 5, , 2. It means that there

Accepted Answer

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

Question 6

Consider the systems with following open loop transfer functions If unity feedback is used, the increasing order of time taken for unit step response to settle is

Accepted Answer

. For the three systems the values of ξωn are 1.8, 2.5 and 2 respectively. Hence values of T are 0.55, 0.4 and 0.5 respectively.

Question 7

When a unit step voltage drives a lag network the output

Accepted Answer

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.

Question 8

In a minimum phase system

Accepted Answer

For stability poles must be in left half plane. Zeros in left half plane lead to minimum phase shift.

Question 9

For the system in the given figure the characteristic equation is

Accepted Answer

Transfer function = . Hence characteristic equation is .

Question 10

Mechanical impedance is the ratio of

Accepted Answer

In force voltage analogy force is analogous to voltage and velocity to current. Just as , force/velocity = mechanical impedance.

Automatic Control Systems Questions