# Multiple choice question for engineering

## Set 1

1. State models presented employed:

a) Physical variables

b) Phase variables

c) Canonical variables

d) All of the mentioned

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2. State model is generally not suitable for measuring:

a) Investigation of system properties

b) Evaluation of time response

c) Real variables

d) Both a and b

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3. ______________ are the techniques for converting general state models into canonical one.

a) Observable

b) Controllable

c) Diagoanlization

d) Cannonical

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4. The values of the characteristic equation is given by:

a) Eigen values

b) State matrix

c) Eigen vector

d) None of the mentioned

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5. The matrix constructed by placing the Eigen vectors together is diagonalizing matrix.

a) True

b) False

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6. The diagonalizing matrix is also known as:

a) Eigen matrix

b) Modal matrix

c) Constant matrix

d) State matrix

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7. In an open loop control system

a) Output is independent of control input

b) Output is dependent on control input

c) Only system parameters have effect on the control output

d) None of the mentioned

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8. Which of the following is exhibited by Root locus diagrams?

a) The poles of the transfer function for a set of parameter values

b) The bandwidth of the system

c) The response of a system to a step input

d) The frequency response of a system

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9. The first order control system, which is well designed, has a

a) Small bandwidth

b) Negative time constant

c) Large negative transfer function pole

d) None of the mentioned

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10. A.C. servomotor is basically a

a) Universal motor

b) Single phase induction motor

c) Two phase induction motor

d) Three phase induction motor

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## Set 2

1. Difference equation model results in:

a) Sampled-data systems

b) Numerical analysis of continuous time systems

c) Continuous time feedback systems

d) Both a and b

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2. Difference equation is used in :

a) Discrete time analysis

b) Continuous time analysis

c) Digital analysis

d) None of the mentioned

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3. Difference equation in discrete systems is similar to the _____________ in continuous systems.

a) Difference equation

b) Differential equation

c) Quadratic equation

d) None of the mentioned

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4. Difference equation solution yields at the sampling instants only:

a) True

b) False

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5. Difference equation technique for higher order systems is used in:

a) Laplace transform

b) Fourier transform

c) Z-transform

d) None of the mentioned

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6. Assertion (A): An LTI discrete system represented by the difference equation. y (n+2)-5y(n+1)+6y(n) =x(n) is unstable.

Reason (R): A system is unstable if the roots of the characteristic equation lie outside the unit circle.

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

b) Both A and R are true but R is NOT the correct explanation of A

c) A is true but R is false

d) A is false but R is false

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7. The poles of a digital filter with linear phase response can lie

a) Only at z =0

b) Only on the unit circle

c) Only inside the unit circle but not at z =0

d) On the left side of Real (z) =0 line

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8. If X(z) =(z+z^{-3})/(z+z^{-1}), then x(n) series has:

a) Alternate 0s

b) Alternate 1s

c) Alternate 2s

d) Alternate -1s

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9. Assertion (A): The stability of the system is assured if the ROC includes the unit circle in z-plane.

Reason (R): For a causal stable system all the poles should be outside the unit circle in the z-plane.

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

b) Both A and R are true bit R is NOT the correct explanation of A

c) A is true but R is false

d) A is false but R is true

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10. Assertion (A): For the rational transfer function H(z) to be causal, stable and causally invertible, both the zeroes and the poles should lie within the unit circle in the z-plane.

Reason (R): For a rational system, ROC is bounded by poles

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

b) Both A and R are true bit R is NOT the correct explanation of A

c) A is true but R is false

d) A is false but R is true

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## Set 3

1. If the Liapunov’s function cannot be found then the system is:

a) Stable

b) Unstable

c) Conditionally stable

d) Marginally stable

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2. Liapunov’s stability analysis is for the :

a) LTI system

b) Time variant system

c) Non-linear system

d) Linear system

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3. The system is unstable for:

a) W (x)>0; x not equal to zero

b) W (0) =0

c) W (x) has continuous partial derivative with respect to all components of x

d) All of the mentioned

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4. Liapunov’s stability for non-linear system is same as the Routh Hurwitz criteria for the linear system.

a) True

b) False

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5. Conditions of ___________ are necessary and sufficient condition for the asymptotic stability of the system.

a) Linear system

b) Krasovskii’s method

c) positive definiteness

d) Variable gradient method

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6. It is difficult to form Liapunov’s function for:

a) Linear system

b) Non-linear

c) Time variant systems

d) Time –invariant systems

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7. If the V is positive definite, for the system to be asymptotically stable, Q should be negative definite.

a) Krasovskii’s method

b) Variable gradient method

c) Constant method

d) Non-variable gradient method

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8. The method which provides considerable flexibility in finding the Liapunov’s function is:

a) Krasovskii’s method

b) Variable gradient method

c) Constant method

d) Non-variable gradient method

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9. Liapunov stability analysis is different from the classical theories approach of stability.

a) True

b) False

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10. For non-linear systems the equation for damping factor as in linear system is called__________

a) Krasovskii’s equation

b) Vander Pol’s equation

c) Constant method

d) Non-variable gradient equation

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## Set 4

1. Which of the following are the not characteristics of the closed loop systems?

a) It does not compensate for disturbance

b) It reduces the sensitivity of plant-parameter variations

c) It does not involve output measurements

d) It does not has the ability to control the system transient response

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2. Which one of the following effect in the system is not caused by negative feedback?

a) Reduction in gain

b) Increased in bandwidth

c) Increase in distortion

d) Reduction in output impedance

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3. Which of the statement is correct with regard to the bandwidth of the control loop system:

a) In systems where the low frequency magnitude in 0 dB on the bode diagram, the bandwidth is measured at the -3 dB frequency

b) The bandwidth is the measurement of the accuracy of the closed loop system

c) The stability is proportional to the bandwidth

d) The system with larger bandwidth provides slower step response and lower fidelity ramp response

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4. Which of the statements are the advantages of closed loop systems over the open loop system:

a) The overall reliability of the open loop system is more than the closed loop system is more than closed loop system.

b) The transient response in closed loop system decays more quickly than in open loop system.

c) In open loop system closing the loop increases the gain of the system

d) In open loop system the effect of parameter variation is reduced

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5. In control system excessive bandwidth is not employed because

a) Noise is proportional to bandwidth

b) It leads to low relative stability

c) It leads to slower time response

d) Noise is proportional to the square of the bandwidth

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6. Feedback control system is basically

a) High pass filter

b) Low pass filter

c) Band pass filter

d) Band stop filter

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7. Which of the following will not decrease as a result of introduction of negative feedback?

a) Instability

b) Bandwidth

c) Overall gain

d) Distortion

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8. As compared to the closed loop system, an open loop system is

a) More stable but less accurate

b) Less stable as well as less accurate

c) More stable as well as more accurate

d) Less stable but more accurate

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9. Insertion of negative feedback in control system affects:

a) The transient response to vanish uniformly

b) The transient response to decay very fast

c) No change in transient response

d) The transient response decays at slow rate

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10. Open loop system is ___________ stable than closed loop system

a) More

b) Less

c) Inclined

d) Exponential

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11. For the gain feedback system, does not affect the system output if KG is :

a) Small

b) Negative

c) One

d) Very large

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12. Determine the sensitivity of the overall transfer function for the system shown in the figure below, at w=1 rad/sec with respect to the feedback path transfer function.

a) 1.11

b) -1.11

c) 2.22

d) -2.22

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13. Primary purpose of using Feedback is :

a) To reduce the sensitivity of the system to parameter variations.

b) To increase the bandwidth of the system

c) To reduce the noise and distortion of the system

d) To increase stability of the system

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## Set 5

1. The mechanism of control of body temperature is non feedback system?

a) True

b) False

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2. Benefits of feedback:

a) Performance of system is greater.

b) Need for system much larger path gain and system instability.

c) Controlled variable accurately follows the desired value

d) Affected by parameter variations

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3. Feedback always increases the gain?

a) True

b) False

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4. Effect of feedback on sensitivity is minimum in:

a) Open loop control system

b) Closed loop control system

c) None of the mentioned

d) Both of the mentioned

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5. Feedback control systems are:

a) Insensitive to both forward and feedback path parameter changes

b) Less sensitive to feedback path parameter changes than to forward path parameter changes

c) Less sensitive to forward path parameter changes that to feedback path parameter changes

d) Equally sensitive to forward feedback path parameter changes

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6. Consider the following statements with respect to the feedback of the control systems:

1. Feedback can improve stability or be harmful to stability if it is not properly applied.

2. Feedback can always improve stability

3. In many situations the feedback can reduce the effect of noise and disturbance on system performance.

4. In general the sensitivity of the system gain of a feedback system of a parameter variation depends on where the parameter is located.

a) 1,2 and 3 only

b) 1,3 and 4 only

c) 1,2 and 4 only

d) 1,2,3 and 4 only

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7. The closed system has higher ________ than open loop control system, this implies increased speed of response.

a) Gain

b) Bandwidth

c) Frequency

d) Speed

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8. Feedback can always reduce the effects of noise and disturbance on system performance?

a) True

b) False

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9. Multiple signals as input can be used in which systems:

a) Feedback systems

b) Non feedback systems

c) Feedforward systems

d) None of the mentioned

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10. Feedback can cause a system that is originally stable to become___________

a) Stable

b) Unstable

c) Conditionally stable

d) Either more stable or unstable