# Multiple choice question for engineering

## Set 1

1. What will be the nature of time response if the roots of the characteristic equation are located on the s-plane imaginary axis?

a) Oscillations

b) Damped oscillations

c) No oscillations

d) Under damped oscilaations

### View Answer

2. Consider a system with transfer function G(s) = s+6/Ks^{2}+s+6. Its damping ratio will be 0.5 when the values of k is:

a) 2/6

b) 3

c) 1/6

d) 6

### View Answer

^{2}+s/K+6/K] Comparing with s

^{2}+2Gw+w

^{2}w= √6/K 2Gw=1/K 2*0.5*√6/K =1/K K=1/6.

3. The output in response to a unit step input for a particular continuous control system is c(t)= 1-e^{-t}. What is the delay time Td?

a) 0.36

b) 0.18

c) 0.693

d) 0.289

### View Answer

_{n->∞}c(t)=1; . Hence Td (at 50% of the final value) is the solution of 0.5=1-e

^{-Td}, and is equal to ln 2 or 0.693 sec.

4. Which one of the following is the most likely reason for large overshoot in a control system?

a) High gain in a system

b) Presence of dead time delay in a system

c) High positive correcting torque

d) High retarding torque

### View Answer

5. For the system 2/s+1, the approximate time taken for a step response to reach 98% of its final value is:

a) 1s

b) 2s

c) 4s

d) 8s

### View Answer

^{-t}] 1.96 = 2[1-e

^{-T}] T= 4sec.

6. The unit step response of a second order system is = 1-e^{-5t}-5te^{-5t} . Consider the following statements:

1. The under damped natural frequency is 5 rad/s.

2. The damping ratio is 1.

3. The impulse response is 25te^{-5t}.

Which of the statements given above are correct?

a) Only 1 and 2

b) Only 2 and 3

c) Only 1 and 3

d) 1,2 and 3

### View Answer

^{2}+10s+25) R(s) = 1/s G(s) = 25/(s

^{2}+10s+25 ) w= √25 w = 5 rad/sec G = 1.

7. The loop transfer function of controller Gc(s) is :

a) 1+0.1s/s

b) -1+0.1s/s

c) –s/s+1

d) s/s+1

### View Answer

8. The peak percentage overshoot of the closed loop system is :

a) 5.0%

b) 10.0%

c) 16.3%

d) 1.63%

### View Answer

^{2}+s+1 C(s)/R(s) = w/ws

^{2}+2Gws+w

^{2}Compare both the equations, w = 1 rad/sec 2Gw = 1 Mp = 16.3 %

9. Consider a second order all-pole transfer function model, if the desired settling time(5%) is 0.60 sec and the desired damping ratio 0.707, where should the poles be located in s-plane?

a) -5+j4√2

b) -5+j5

c) -4+j5√2

d) -4+j7

### View Answer

10. Which of the following quantities give a measure of the transient characteristics of a control system, when subjected to unit step excitation.

1. Maximum overshoot

2. Maximum undershoot

3. Overall gain

4. Delay time

5. Rise time

6. Fall time

a) 1,3 and 5

b) 2, 4 and 5

c) 2,4 and 6

d) 1,4 and 5

### View Answer

## Set 2

1. The standard second order system to a unit step input shows the 0.36 as the first peak undershoot, hence its second overshoot is:

a) 0.135

b) 0.216

c) 0.1296

d) 0.116

### View Answer

2. Consider the input with the inputs 4 u(t) and the impulse response 5 +7 , the time constants of the output are,

a) 0.2, 0.33 and 0.5

b) 4.5 and 7

c) 0.2, 0.4 and 0.7

d) 0.2, 0.1 and 0.25

### View Answer

3. In a second order feedback control system natural frequency and damping

a) Can be designed by changing the gain of the individual system

b) Cannot be designed by changing the gain of the individual system

c) Are independent on the type of input excitation

d) None of the mentioned

### View Answer

4. Undamped natural frequency of a second order system has the following influence on the response due to various excitations:

a) Increase in speed of response and decrease sensitivity

b) Decrease in speed of response and increase sensitivity

c) Has no influence in the dynamic response

d) Increase oscillatory behavior

### View Answer

5. Normalized response of a dynamic system refers to:

a) Characteristic feature of a response due to specific excitation irrespective of its amplitude

b) Response of dynamic system divided by its maximum value

c) Response of dynamic system divided by a standard value

d) None of the mentioned

### View Answer

6. The transfer function of a system is G(s) = 100/(s+1) (s+100). For a unit step input to the system the approximate settling time for 2% criterion is:

a) 100 sec

b) 4 sec

c) 1 sec

d) 0.01 sec

### View Answer

7. The characteristic equation of a control system is s(s^{2}+ 6s+13)+K=0. The value of k such that the characteristic equation has a pair of complex roots with real part -1 will be :

a) 10

b) 20

c) 30

d) 40

### View Answer

8. Normalized difference between the time response peak and steady state output is ______________

a) Maximum peak overshoot

b) Damping factor

c) Minimum peak overshoot

d) Undershoot

### View Answer

9. Rise time, Peak time, maximum peak overshoot, settling time, and steady state error are mutually dependent.

a) True

b) False

### View Answer

10. Control system are normally designed to be:

a) Overdamped

b) Under damped

c) Un damped

d) Critically damped

### View Answer

## Set 3

1. Which of the following can be used as a tacho generator in control systems?

a) Microsyn

b) DC servomotor

c) AC servomotor

d) Magnetic Amplifier

### View Answer

2. Consider the function F (s)= 5/s(s^{2}+3s+2), the initial value of f(t) is:

a) 5

b) 5/2

c) 5/3

d) 0

### View Answer

3. An electric motor is developing 10KW at a speed of 900rpm. The torque available at the shaft is:

a) 106 N-m

b) 66 N-m

c) 1600 N-m

d) 90 N-m

### View Answer

4. Assertion (A): Many of the linear control system transfer function do not have poles or zeroes in the right half s-plane.

Reason (R): These are called minimum phase transfer function.

a) Both A and R are true and R is correct explanation of A

b) Both A and R are true and R is not correct Explanation of A

c) A is True and R is false

d) A is False and R is true

### View Answer

5. The tacho meter has sensitivity of 5V/1000rpm. The gain constant of the tacho meter is:

a) 0.48V/rad/sec

b) 0.048V/rad/sec

c) 4.8V/rad/sec

d) 48V/rad/sec

### View Answer

6. The closed loop transfer function of a unity negative feedback system is 100/(s^{2}+8s+100). Its open loop transfer function is:

a) 100/s+8

b) 1/s^{2}+8s

c) 100/s^{2}-8s

d) 100/s^{2}+8s

### View Answer

7. The impulse response of a linear LTI system is given as g (t) = e^{(-t)}The transfer function of the system is equal to:

a) 1/s

b) 1/s(s+1)

c) 1/(s+1)

d) s/(s+1)

### View Answer

8. In a closed loop for which the output is the speed of the motor, the output rate control can be used to:

a) Limit the speed of the motor

b) Limit the torque output of the motor

c) Reduce the damping of the system

d) Limit the acceleration of the motor

### View Answer

9. In servo-system, the device used for derivative feedback is known as:

a) Synchro

b) Servomotor

c) Potentiometer

d) Tacho generator

### View Answer

10. The transfer function of any stable system which has no zeros or poles in the right half of the s-plane is said to be:

a) Minimum phase transfer function

b) Non-minimum phase transfer function

c) Minimum phase frequency response function

d) Minimum gain transfer function

### View Answer

## Set 4

1. The systems with equation such as dx/dt =F (x) are called:

a) Stable systems

b) Control systems

c) Autonomous systems

d) Unstable control system

### View Answer

2. The points at which derivatives of all the state variables are zero are:

a) Singular points

b) Nonsingular points

c) Poles

d) Zeros

### View Answer

3. The system if kept in the singular points will continue to lie on these points undisturbed.

a) True

b) False

### View Answer

4. A system is stable with zero input if:

a) The resulting trajectory tends towards the equilibrium state.

b) If for the bounded input output is also bounded

c) It is a free system

d) It is forced system

### View Answer

5. A Forced system is stable if:

a) The resulting trajectory tends towards the equilibrium state.

b) If for the bounded input output is also bounded

c) It is a free system

d) It is forced system

### View Answer

6. In non-linear systems forced and free responses are:

a) Related

b) Not related

c) Contemporary

d) None of the mentioned

### View Answer

7. The linear autonomous systems:

a) Have one equilibrium state

b) Their behavior determines the qualitative behavior of the s-plane

c) System behavior for small deviations about the equilibrium point may be different from the large deviation

d) Both a and b

### View Answer

8. The non-linear system

a) Have one equilibrium state

b) Their behavior determines the qualitative behavior of the s-plane

c) System behavior for small deviations about the equilibrium point may be different from the large deviation

d) Both a and b

### View Answer

9. The system is stable at origin if for every initial state which is sufficiently close to the origin remains near the origin for all t then the system is :

a) Asymptotically stable

b) Asymptotically stable in the large

c) Stable

d) Unstable

### View Answer

10. If x (t) approaches near the origin as t tends to infinity then the system is :

a) Asymptotically stable

b) Asymptotically stable in the large

c) Stable

d) Unstable

### View Answer

## Set 5

1. A phase lead compensation leads to:

a) Increase in overshoot

b) Reduction in bandwidth of closed loop system

c) Reduction in rise time of closed loop system

d) Reduction in gain margin

### View Answer

2. PD controller is used to compensate system. Compared to the uncompensated system, the compensated system has:

a) A higher type number

b) Reduced damping

c) Higher noise amplification

d) Large transient overshoot

### View Answer

3. P+D controller:

a) Introduces offset

b) Increases bandwidth

c) Increases margin of stability

d) Reduces velocity constant

### View Answer

4. Proportional controller:

a) Introduces offset

b) Increases bandwidth

c) Increases margin of stability

d) Reduces velocity constant

### View Answer

5. The transfer function of a lead controller is 1+20s/1+5s. The high frequency magnitude of the lead controller to dB is ___________

a) 1

b) 2

c) 3

d) 4

### View Answer

6. Controllers play the following role in control system:

a) They amplify the signals going to the actuator

b) They act on the error signal coming out of the summing junction and output a suitable to the actuator

c) They try to reduce steady state error optimizes overshoot.

d) All of the mentioned

### View Answer

7. The transfer function of the compensator is s+4/s+16. The maximum phase lead frequency and the corresponding phase is :

a) 6 rad/sec, 36.87°

b) 8 rad/sec, 36.87°

c) 6 rad/sec, -36.87°

d) 8 rad/sec, -36.87°

### View Answer

8. Response to error is very fast for integral controller.

a) True

b) False

### View Answer

9. Consider the following statements:

1. Integral controller improves steady state response

2. By use of proportional controller, maximum peak overshoot decreases

3. Type and order of system reduces by one for derivative controller

4. Integral controller makes the system less stable in transient state due to oscillations

Select the correct answer using the codes given below:

a) 1,3 and 4

b) 1,2 and 3

c) 2.3 and 4

d) 1,2 and 4

### View Answer

10. Rate mode controller is also known as ______________ controller mode.

a) Anticpatory

b) Delay

c) Integral

d) Derivative