# Electronics and Communication Engineering - Automatic Control Systems

### Exercise :: Automatic Control Systems - Section 2

1.

The first column of a Routh array is How many roots of the corresponding characteristic equation are in left half s-plane?

 A. 2 B. 3 C. 4 D. 5

Explanation:

Total number of roots is 5. Since two sign changes in first column, two roots are in right half plane.

Hence 3 roots in left half plane.

2.

For the given figure, time constant RC = t. Then  A. t2s2 + 2ts + 1 B. C. ts2 + 1 D. Explanation: .

3.

The entries in the first column of Routh array of a fourth order are 5, 2, - 0.1, 2, 1. The number of poles in the right half plane are

 A. 1 B. 2 C. 3 D. 4

Explanation:

Two sign changes and hence two poles in right half plane.

4.

In Bode diagram (log magnitude plot) the factor (jω)n in the transfer function gives a line having slope

 A. 20 dB/decade B. 20n dB/decade C. D. -20n dB/decade

Explanation:

For (jω)n term the slope is (20 n) dB/decade.

5.

The magnitude of transport lag factor is always zero.

 A. True B. False