# Electronics and Communication Engineering - Automatic Control Systems

### Exercise :: Automatic Control Systems - Section 4

1.

Examine the following statements

1. Air and gases are compressible.
2. Air, gases and some liquids are compressible.
3. Oil can function as hydraulic fluid as well as lubricator.
Which of the above statements are correct?

 A. 3 only B. 2 and 3 only C. 1 and 3 only D. 2 only

Explanation:

No answer description available for this question. Let us discuss.

2.

Which control action is also called rate control?

 A. Proportional B. Derivative C. Integral D. Proportional plus integral

Explanation:

No answer description available for this question. Let us discuss.

3.

The gain margin for a stable system

 A. has a positive decibel value B. has a negative decibel value C. has a large negative decibel value D. none of the above

Explanation:

For a stable system gain margin is positive. Therefore decibel value is also positive.

4.

The signal flow graph of a system is shown in the given figure. The effect of disturbance TD can be reduced by A. increasing G2 (s) B. decreasing G2 (s) C. increasing G1 (s) D. decreasing G1 (s)

Explanation:

If G1(s) is increased, input is amplified more while disturbance remains the same.

5.

For overdamped systems a quadratic factor in transfer function can be replaced by two first order factors with real poles

 A. True B. False