Magme Guru: Control System

Showing posts with label Control System. Show all posts

Showing posts with label Control System. Show all posts

Thursday, April 16, 2020

CONTROL SYSTEM MCQS SET 37

Electronics Engineering April 16, 2020

CONTROL SYSTEM MCQS SET 37

CONTROL SYSTEM MCQS SET 37

1. For a type one system, the steady – state error due to step input is equal to
a) Infinite             b) Zero           c) 0.25              d) 0.5
Answer: b

2. The equation 2s4+s3+3s2+5s+10=0 has roots in the left half of s–plane:
a) One            b) Two         c) Three      d) Four
Answer: b

3. If the Nyquist plot of the loop transfer function G (s)H (s) of a closed-loop system encloses the (1, j0) point in the G (s)H (s) plane, the gain margin of the system is
a) Zero             b) Greater than zero         c) Less than zero      d) Infinity
Answer: c

4. Consider the function F (s) =5/s (s2+s+2) , where F (s) is the Laplace transform f (t). Then the final value theorem is equal to
a) 5             b) 5/2               c) Zero            d) Infinity
Answer: b
5. The transfer function of a phase-lead controller is given by
a) (1+aTs)/(1+Ts) , a>1 T>0            b) (1+aTs)/(1+Ts) , a<1 T>0
c) (1-aTs)/(1+Ts) , a>1 T>0              d) (1±Ts)/(1+Ts) , a<1 T>0
Answer: a

6. If the system matrix of a linear time invariant continuous system is given by
Its characteristic equation is given by:
a) s2+5s+3=0              b) s2-3s-5=0              c) s2+3s+5=0

d) s2+s+2=0

7. Given a unity feedback control system with G (s) = K/s(s+4), the value of K for which the damping ratio is 0.5.
a) 1         b) 16          c) 64                d) 32
Answer: b

8. The LVDT is used in the measurement of:
a) Displacement          b) Acceleration           c) Velocity         d) Humidity
Answer:a

9. A system with gain margin close to unity and phase margin close to zero is :
a) Highly stable           b) Oscillatory    c) Relatively stable      d) Unstable
Answer: c

CONTROL SYSTEM MCQS SET 36

Electronics Engineering April 16, 2020

CONTROL SYSTEM MCQS SET 36

CONTROL SYSTEM MCQS SET 36

1. The range of K for the stability of system is 0<K<100. For K =10, The gain Margin of the system
a) 10         b) 5           c) 0.1             d) 0.5
Answer: a

2. The frequency at which the Nyquist diagram cuts the unit circle is known as:
a) Gain crossover frequency
b) Phase crossover frequency
c) Damping frequency
d) Corner frequency
Answer: a

3. The forward path transfer function of a unity feedback system is given by G(s) = 1/(1+s)^2. What is the phase margin of the system?
a) –π rad          b) 0 rad           c) π/2 rad          d) π rad
Answer: d

4. Consider the following statements:
1. The delay time is the time required to reach 50% of the final value in the first time.
2. The rise time is the time required for the response to rise from 10% to 90% of its final value for underdamped systems.
3. The rise time is the time required for the response to rise from 0 to 100% for the underdamped systems.
Which of these statements are correct?
a) 1,2 and 3 only                     b) 1 and 2 only
c) 1 and 3 only                         d) 2 and 3 only negative real axis
Answer: c

5. For minimum phase systems:
a) Pole must lie on left plane             b) Zeroes must lie on left plane
c) Poles and zeroes must lie on left plane
d) Both must lie on right plane
Answer: c

6. For non-minimum phase systems:
a) Poles and zeroes must lie on the right s-plane
b) Zeroes must lie on right of s-plane
c) Both lie on left of s-plane
d) Poles must be on the left and zeroes can be on the right s –plane.
Answer: d

7. For all-pass systems:
a) Poles must lie on right of the s-plane
b) Zeroes must lie on the left of s-plane
c) Poles must lie on the left and zeroes on the mirror image of the pole can be on the right
d) None of the mentioned
Answer: c

8. All pass system and minimum phase system constitute_________________
a) Pole must lie on left plane
b) Minimum phase system
c) Non-minimum phase system
d) Both must lie on right plane
Answer: c

9. Minimum phase systems have unique relationship between its phase and magnitude curves
a) True             b) False
Answer: a

10. The impulse response of a LTI system is a unit step function, then the corresponding transfer function is
a) 1/s             b) 1/s2                  c) 1                  d) s
Answer: a

CONTROL SYSTEM MCQS SET 35

Electronics Engineering April 16, 2020

CONTROL SYSTEM MCQS SET 35

CONTROL SYSTEM MCQS SET 35

1. All the constant N-circles in G planes cross the real axis at the fixed points. Which are these points?
a) -1 and origin        b) Origin and +1         c) -0.5 and 0.5      d) -1 and +1
Answer: a

2. Consider the following statements:
Nichol’s chart gives information about.
i. Closed loop frequency response.
ii. The value of the peak magnitude of the closed loop frequency response Mp.
iii. The frequency at which Mp occurs.
Which of the above statements are correct?
a) 2 and 3          b) 1 and 2            c) 1 and 3          d) 1,2 and 3
Answer: d

3. Which one of the following statements is correct? Nichol’s chart is useful for the detailed study analysis of:
a) Closed loop frequency response
b) Open loop frequency response
c) Close loop and open loop frequency responses
d) None of the above
Answer: a

4. In a bode magnitude plot, which one of the following slopes would be exhibited at high frequencies by a 4th order all-pole system?
a) -80dB/decade          b) -40 dB/decade         c) 40 dB/decade
d) 80 dB/decade
Answer: a

5. Frequency range of bode magnitude and phases are decided by :
a) The lowest and higher important frequencies of dominant factors of the OLTF
b) The lowest and highest important frequencies of all the factors of the open loop transfer function
c) Resonant frequencies of the second factors
d) None of the above
Answer: d

6. OLTF contains one zero in right half of s-plane then
a) Open loop system is unstable
b) Close loop system is unstable
c) Close loop system is unstable for higher gain
d) Close loop system is stable
Answer: c

7. The critical value of gain for a system is 40 and gain margin is 6dB. The system is operating at a gain of:
a) 20            b) 40           c) 80        d) 120
Answer: a
8. Nichol’s chart is useful for the detailed study and analysis of:
a) Closed loop frequency response
b) Open loop frequency response
c) Close loop and open loop frequency responses
d) open loop and Close loop frequency responses
Answer: a

9. The roots of the characteristic equation of the second order system in which real and imaginary part represents the :
a) Damped frequency and damping
b) Damping and damped frequency
c) Natural frequency and damping ratio
d) Damping ratio and natural frequency
Answer: b

10. A minimum phase unity feedback system has a bode plot with a constant slope of -20dB/decade for all frequencies. What is the value of the maximum phase margins of the system?
a) 0°             b) 90°         c) -90°           d) 180°
Answer: b

CONTROL SYSTEM MCQS SET 34

Electronics Engineering April 16, 2020

CONTROL SYSTEM MCQS SET 34

CONTROL SYSTEM MCQS SET 34

1. For the transfer function
G(s) H(s) = 1 / s(s+1) (s+0.5), the phase cross-over frequency is
a) 0.5 rad/sec         b) 0.707 rad/sec          c) 1.732 rad/sec
d) 2 rad/sec
Answer: b

2. The gain margin (in dB) of a system having the loop transfer function
G(s) H(s) = 2 / s(s+1) is
a) 0             b) 3            c) 6               d) 8
Answer: d

3. The gain margin for the system with open loop transfer function
G(s) H(s) = G(s) =2(1+s) / s2 is
a) 8                b) 0         c) 1                d) -8
Answer: 0

4. Statement 1: In constant M circles, as M increases from 1 to 8 radius of circle increases from 0 to 8 and Centre shifts from (-1,0) to (-8,0)
Statement 2: The circle intersects real axis at point (-1/2, 0)
a) Statement 1 is TRUE, 2 is FALSE
b) Statement 1 is FALSE, 2 is TRUE
c) Statement 1 & 2 TRUE
d) Statement 1 & 2 FALSE
Answer: d

5. Assertion (A): Relative stability of the system reduces due to the presence of transportation lag.
Reason (R): Transportation lag can be conveniently handled by Bode plot.
a) Both A and R are true but R is correct explanation of A
b) Both A and R are true but R is correct explanation of A
c) A is true but R is false
d) A is false but R is true
Answer: b

6. Assertion (A): The phase angle plot in Bode diagram is not affected by the variation in the gain of the system.
Reason(R): The variation in the gain of the system has no effect on the phase margin of the system.
a) Both A and R are true but R is correct explanation of A
b) Both A and R are true but R is correct explanation of A
c) A is true but R is false
d) A is false but R is true
Answer: c

7. A system has poles at 0.01 Hz, 1 Hz and 80Hz, zeroes at 5Hz, 100Hz and 200Hz. The approximate phase of the system response at 20 Hz is:
a) -90°                 b) 0°               c) 90°             d) -180°
Answer: a

8. The constant M-circle represented by the equation x^2+2.25x+y^2=-1.25 has the value of M equal to:
a) 1            b) 2           c) 3             d) 4
Answer: c

9. What is the value of M for the constant M circle represented by the equation 8x^2+18x+8y^2+9=0?
a) 0.5              b) 2                c) 3         d) 8
Answer: c

10. The constant N loci represented by the equation x^2+x+y^2=0 is for the value of phase angle equal to:
a) -45°             b) 0°             c) 45°              d) 90°
Answer: d

CONTROL SYSTEM MCQS SET 33

Electronics Engineering April 16, 2020

CONTROL SYSTEM MCQS SET 33

CONTROL SYSTEM MCQS SET 33

1. The constant M circle for M=1 is the
a) straight line x=-1/2              b) critical point (-1j0)
c) circle with r= 0.33                d) circle with r=0.67
Answer: a

2. The polar plot of a transfer function passes through the critical point (-1,0). Gain margin is
a) Zero       b) -1dB         c) 1dB              d) Infinity
Answer: a

3. Consider the following statements:
1. The effect of feedback is to reduce the system error
2. Feedback increases the gain of the system in one frequency range but decreases in another
3. Feedback can cause a system that is originally stable to become unstable
Which of these statements are correct.
a) 1,2 and 3
b) 1 and 2
c) 2 and 3
d) 1 and 3
Answer: c

4. The open loop transfer function of a system is G(s) H(s)= K / (1+s)(1+2s)(1+3s)
The phase cross over frequency ωc is
a) V2
b) 1
c) Zero
d) V3
Answer: b

5. If the gain of the open-loop system is doubled, the gain margin
a) Is not affected
b) Gets doubled
c) Becomes half
d) Becomes one-fourth
Answer: a

6. The unit circle of the Nyquist plot transforms into 0dB line of the amplitude plot of the Bode diagram at
a) 0 frequency
b) Low frequency
c) High frequency
d) Any frequency
Answer: d

7. Consider the following statements:
The gain margin and phase margin of an unstable system may respectively be
1. Positive, positive
2. Positive, negative
3. Negative, positive
4. Negative, negative
Of these statements
a) 1 and 4 are correct
b) 1 and 2 are correct
c) 1, 2 and 3 are correct
d) 2,3 and 4 are correct
Answer: d

8. If a system has an open loop transfer function
1-s / 1+s, then the gain of the system at frequency of 1 rad/s will be
a) 1            b) ½          c) Zero               d) -1
Answer: d

9. The polar plot of the open loop transfer function of a feedback control system intersects the real axis at -2. The gain margin of the system is
a) -5dB              b) 0dB            c) -6dB               d) 40dB
Answer: c

10. The corner frequencies are
a) 0 and 1         b) 0 and 2         c) 0 and 1              d) 1 and 2
Answer: d

Thursday, February 13, 2020

CONTROL SYSTEM MCQs SET 32

Electronics Engineering February 13, 2020

CONTROL SYSTEM MCQs SET 32

CONTROL SYSTEM MCQs SET 32

1. If the impulse response in absolutely integrable then the system is:
a) Absolutely stable
b) Unstable
c) Linear
d) Stable

Answer: a

2. The roots of the transfer function do not have any effect on the stability of the system.
a) True
b) False

Answer: b

3. Roots with higher multiplicity on the imaginary axis makes the system:
a) Absolutely stable
b) Unstable
c) Linear
d) Stable

Answer: b

4. Roots on the imaginary axis makes the system:
a) Stable
b) Unstable
c) Marginally stable
d) Linear

Answer: c

5. If the roots of the have negative real parts then the response is ____________
a) Stable
b) Unstable
c) Marginally stable
d) Bounded

Answer: d

6. If root of the characteristic equation has positive real part the system is:
a) Stable
b) Unstable
c) Marginally stable
d) Linear

Answer: b

7. A linear system can be classified as:
a) Absolutely stable
b) Conditionally stable
c) Unstable
d) All of the mentioned

Answer: d

8. ___________ is a quantitative measure of how fast the transients die out in the system.
a) Absolutely stable
b) Conditionally stable
c) Unstable
d) Relative Stability

Answer: d

9. The techniques of linear system can be used in the non-linear system entirely:
a) True
b) False

Answer: a

10. The disadvantages of the linear system are:
a) The constraints on the linear operation over wide range demands unnecessarily high quality.
b) The restriction to the linear theory may inhibit the designer’s curiosity to deliberately introduce the non-linear components.
c) Practically systems are non-linear
d) All of the mentioned

Answer: d

CONTROL SYSTEM MCQs SET 31

Electronics Engineering February 13, 2020

CONTROL SYSTEM MCQs SET 31

CONTROL SYSTEM MCQs SET 31

1. Constant M- loci:
a) Constant gain and constant phase shift loci of the closed-loop system.
b) Plot of loop gain with the variation in frequency
c) Circles of constant gain for the closed loop transfer function
d) Circles of constant phase shift for the closed loop transfer function

Answer: d

2. Constant N-loci:
a) Constant gain and constant phase shift loci of the closed-loop system.
b) Plot of loop gain with the variation in frequency
c) Circles of constant gain for the closed loop transfer function
d) Circles of constant phase shift for the closed loop transfer function

Answer: c

3. Nichol’s chart:
a) Constant gain and constant phase shift loci of the closed-loop system.
b) Plot of loop gain with the variation in frequency
c) Circles of constant gain for the closed loop transfer function
d) Circles of constant phase shift for the closed loop transfer function

Answer: b

4. Stability of a system implies that:
a) Small changes in the system input does not result in large change in system output
b) Small changes in the system parameters does not result in large change in system output
c) Small changes in the initial conditions does not result in large change in system output
d) All of the above mentioned

Answer: d

5. A linear time invariant system is stable if:
a) System in excited by the bounded input, the output is also bounded
b) In the absence of input output tends zero
c) Both a and b
d) System in excited by the bounded input, the output is not bounded

Answer: c

6. Asymptotic stability is concerned with:
a) A system under influence of input
b) A system not under influence of input
c) A system under influence of output
d) A system not under influence of output

Answer: b

7. Bounded input and Bounded output stability notion concerns with :
a) A system under influence of input
b) A system not under influence of input
c) A system under influence of output
d) A system not under influence of output

Answer: a

8. If a system is given unbounded input then the system is:
a) Stable
b) Unstable
c) Not defined
d) Linear

Answer: c

9. Linear mathematical model applies to:
a) Linear systems
b) Stable systems
c) Unstable systems
d) Non-linear systems

Answer: b

10. For non-linear systems stability cannot be determined due to:
a) Possible existence of multiple equilibrium states
b) No correspondence between bounded input and bounded output stability and asymptotic stability
c) Output may be bounded for the particular bounded input but may not be bounded for the bounded inputs
d) All of the mentioned

Answer: d

CONTROL SYSTEM MCQs SET 30

Electronics Engineering February 13, 2020

CONTROL SYSTEM MCQs SET 30

CONTROL SYSTEM MCQs SET 30

1. Linear lumped parameter models are not valid under situations as:
a) Transmission pipe between the hydraulic pump and the motor causes a time lag in transportation of oil from pump to motor
b) Transmission of heat by conduction or convection produces serious transportation lag
c) Both of the mentioned
d) None of the mentioned

Answer: c

72. Practically all the systems have transportation lag:
a) True
b) False

Answer: b

3. Transportation lag causes:
a) Instability in system
b) Stability in system
c) System remains unaffected
d) Bandwidth increases

Answer: a

4. Scientist Bode have contribution in:
a) Asymptotic plots
b) Polar plots
c) Root locus technique
d) Constant M and n circle

Answer: a
5. Scientist Evans have contribution in:
a) Asymptotic plots
b) Polar plots
c) Root locus technique
d) Constant M and n circle

Answer: c

6. Scientist Nyquist have contribution in:
a) Asymptotic plots
b) Polar plots
c) Root locus technique
d) Constant M and n circle

Answer: b

7. For a stable closed loop system, the gain at phase crossover frequency should always be:
a) < 20 dB
b) < 6 dB
c) > 6 dB
d) > 0 dB

Answer: d

8. Which one of the following methods can determine the closed loop system resonance frequency operation?
a) Root locus method
b) Nyquist method
c) Bode plot
d) M and N circle

Answer: d

9. If the gain of the open loop system is doubled, the gain of the system is:
a) Not affected
b) Doubled
c) Halved
d) One fourth of the original value

Answer: a

10. Which one of the following statements is correct?
Nichol’s chart is useful for the detailed study of:
a) Closed loop frequency response
b) Open loop frequency response
c) Close loop and open loop frequency responses
d) None of the mentioned

Answer: a

CONTROL SYSTEM MCQs SET 29

Electronics Engineering February 13, 2020

CONTROL SYSTEM MCQs SET 29

CONTROL SYSTEM MCQs SET 29

1. The characteristic equation of a control system is given as 1+ K(s+4)/s(s+7)(s2+2s+2)=0. The real axis intercept for root locus asymptote is:
a) -2.25
b) -1
c) -1.67
d) 0

Answer: c

2. The OLTF of a unity feedback system is K(s+2)(s+4)/(s+5)(s+6) the angle of arrival of the root loci as s =-2, and s =-4 respectively are:
a) 0°,180°
b) 180°,0°
c) 90°,180°
d) 180°, 90°

Answer: b

3. The characteristic equation is s3+14s2+(45+K)s+K =0, centroid is located at (-x,0) then the value of x is ____________
a) 1
b) 2
c) 3
d) 4

Answer: b

4. Consider the points s1 =-3+4j and s2 = -3-2j in the s-plane. Then, for a system with the open loop transfer function G(s)H(s) =K/(s+1)4.
a) S1 is on the root locus but s2 is not
b) S2 is on the root locus but s1 is not
c) Both s1 and s2 are not on the root locus
d) Neither s1 nor s2 is on the root locus

Answer: b

5. The characteristic equation of a control system is given by s(s+4)(s2+2s+s) +k(s+1) =0. What are the angles of the asymptotes for the root loci
a) 60°, 180°, 300°
b) 0°, 180°, 300°
c) 120°, 180°, 240°
d) 0°, 120°, 240°

Answer: a

6. The characteristic equation of a feedback control system is given by s3+5s2+(K+6)s+K=0. In the root loci diagram, the asymptotes of the root loci for large K meet at a point in the s plane whose coordinates are:
a) (2,0)
b) (-1,0)
c) (-2,0)
d) (-3,0)

Answer: c

7. The root locus diagram has loop transfer function G(s)H(s) = K/ s(s+4)(s2+4s+5) has
a) No breakaway points
b) Three real breakaway points
c) Only one breakaway points
d) One real and two complex breakaway points

Answer: b

8. For asymptotes passing from breakaway point then this point is also centroid
a) True
b) False

Answer: a

9. Transportation lag is seen in systems:
a) Amount to be transferred in large
b) Time take to transfer is large
c) Inefficiency of the process
d) Errors

Answer: b

10. Mediums responsible for transportation lag are:
a) Lines
b) Pipes
c) Belt conveyors
d) All of the mentioned

Answer: d

CONTROL SYSTEM MCQs SET 28

Electronics Engineering February 13, 2020

CONTROL SYSTEM MCQs SET 28

CONTROL SYSTEM MCQs SET 28

1. The addition of open loop zero pulls the root loci towards:
a) The left and therefore system becomes more stable
b) The right and therefore system becomes unstable
c) Imaginary axis and therefore system becomes marginally stable
d) The left and therefore system becomes unstable

Answer: a

2. If root loci plots of a particular control system do not intersect the imaginary axis at any point, then the gain margin of the system will be:
a) 0
b) 0.707
c) 1
d) Infinite

Answer: d

3. When the number of poles is equal to the number of zeroes, how many branches of root locus tends towards infinity?
a) 1
b) 2
c) 0
d) Equal to number of zeroes

Answer: c

4. With reference to root locus, the complex conjugate roots of the characteristic equation of the O.L.T.F. given below G(s)H(s) =K(s+3)/(s+1)2, lie on
a) Straight line
b) Parabola
c) Circle
d) Semi-circle

Answer: c

5. Determine the centroid of the root locus for the system having G(s)H(s) = K/(s+1)(s2+4s+5)
a) -2.1
b) -1.78
c) -1.66
d) -1.06

Answer: c

6. The loop transfer function of an LTI system is G(s)H(s) =K(s+1)(s+5)/s(s+2)(s+3). For K>0, the point on the real axis that does not belong to the root locus of the system is
a) -0.5
b) -2.5
c) -3.5
d) -5.5

Answer: c

7. The angles of asymptotes of the root loci of the equation s3+5s2+(K+2)s+K=0 are:
a) 0° and 270°
b) 0° and 180°
c) 90° and 270°
d) 90° and 180°

Answer: c

8. The intersection of asymptotes of root loci of a system with open loop transfer function G(s)H(s) = K/s(s+1)(s+3) is
a) 1.44
b) 1.33
c) -1.44
d) -1.33

Answer: d

9. If a feedback control system has its open loop transfer function G(s)H(s) = K/(s-2)(s2+3s+5) has the root locus plot which intersects the imaginary axis at s =0, then the value of K at this point will be
a) -5
b) 10
c) 5
d) -10

Answer: b

10. The open loop transfer function of the feedback control system is given by G(s) =K(s+3)/s(s+4)2(s+5)(s+6). The number of asymptotes and the centroid of asymptotes of the root loci of closed loop system is
a) 4 and (-4,0)
b) 3 and (-12,0)
c) -4 and (-4,0)
d) -3 and (-12,0)

Answer: a

CONTROL SYSTEM MCQs SET 27

Electronics Engineering February 13, 2020

CONTROL SYSTEM MCQs SET 27

CONTROL SYSTEM MCQs SET 27

1. Consider the following statements regarding root loci:
a) All root loci start from the respective poles of G(s) H(s)
b) All root loci end at the respective zeros of G(s) H(s) or go to infinity
c) The root loci are symmetrical about the imaginary axis of the s-plane
d) All root loci start and end from the respective poles of G(s) H(s) or go to infinity

Answer: b

2. Number of roots of characteristic equation is equal to the number of ______________
a) Branches
b) Root
c) Stem
d) Poles

Answer: a
3. Which of the following statements are correct?
a) Root locus is for the negative feedback systems
b) Complementary root locus is for the positive feedback systems
c) Root locus is for the negative feedback and Complementary root locus is for the positive feedback systems
d) Complementary root locus is for the negative feedback systems

Answer: c

4. Consider the loop transfer function K(s+6)/(s+3)(s+5) In the root locus diagram the centroid will be located at:
a) -4
b) -1
c) -2
d) -3

Answer: c

5. Which one of the following applications software’s is used to obtain an accurate root locus for?
a) LISP
b) MATLAB
c) dBase
d) Oracle

Answer: b
6. Which one of the following is not the property of root loci?
a) The root locus is symmetrical about imaginary axis
b) They start from the open loop poles and terminate at the open loop zeroes
c) The breakaway points are determined from dK/ds = 0
d) Segments of the real axis are the part of the root locus if and only is the total number of real poles and zeroes to their right is odd.

Answer: a
7. The breakaway point calculated mathematically must always lie on the root locus.
a) True
b) False

Answer: a

8. What is the number of the root locus segments which do not terminate on zeroes?
a) The number of poles
b) The number of zeroes
c) The difference between the number of poles and zeroes
d) The sum of the number of poles and the number of the zeroes

Answer: c

9. Which one of the following are correct?
The root locus is the path of the roots of the characteristic equation traced out in the s-plane?
a) As the input of the system is changed
b) As the output of the system is changed
c) As a system parameter is changed
d) As the sensitivity is changed

Answer: c

10. If the gain of the system is reduced to a zero value, the roots of the system in the s-plane,
a) Coincide with zero
b) Move away from zero
c) Move away from poles
d) Coincide with the poles

Answer: d

CONTROL SYSTEM MCQs SET 26

Electronics Engineering February 13, 2020

CONTROL SYSTEM MCQs SET 26

CONTROL SYSTEM MCQs SET 26

1. An underdamped second order system with negative damping will have the roots :
a) On the negative real axis as roots
b) On the left hand side of complex plane as complex roots
c) On the right hand side of complex plane as complex conjugates
d) On the positive real axis as real roots

Answer: c
2. Given a unity feedback system with G (s) =K/ s (s+4). What is the value of K for a damping ratio of 0.5?
a) 1
b) 16
c) 4
d) 2

Answer: b

3. How can the steady state error can be reduced?
a) By decreasing the type of the system
b) By increasing system gain
c) By decreasing the static error constant
d) By increasing the input

Answer: d

4. Which one of the following statements is not correct?
a) Root loci can be used for analyzing stability and transient performance
b) Root loci provide insight into system stability and performance
c) Shape of the root locus gives idea of type of controller needed to meet design specification
d) Root locus can be used to handle more than one variable at a time

Answer: d

5. Root locus of s(s+2)+K(s+4) =0 is a circle. What are the coordinates of the center of this circle?
a) -2,0
b) -3,0
c) -4,0
d) -5,0

Answer: c

6. The main objective of drawing root locus plot is :
a) To obtain a clear picture about the open loop poles and zeroes of the system
b) To obtain a clear picture about the transient response of feedback system for various values of open loop gain K
c) To determine sufficient condition for the value of ‘K’ that will make the feedback system unstable
d) Both b and c

Answer: d

7. While increasing the value of gain K, the system becomes
a) Less stable
b) More stable
c) Unstable
d) Absolute stable

Answer: a

8. The addition of open loop poles pulls the root locus towards:
a) The right and system becomes unstable
b) Imaginary axis and system becomes marginally stable
c) The left and system becomes unstable
d) The right and system becomes unstable

Answer: d

9. Root locus is used to calculate:
a) Marginal stability
b) Absolute stability
c) Conditional stability
d) Relative stability

Answer: d

10. Routh Hurwitz criterion is better than root locus.
a) True
b) False

Answer: b

CONTROL SYSTEM MCQs SET 25

Electronics Engineering February 13, 2020

CONTROL SYSTEM MCQs SET 25

CONTROL SYSTEM MCQs SET 25

1. Practically all the elements are:
a) Linear
b) Non-linear
c) Exponential
d) None of the mentioned

Answer: b

2. The need of assuming non-linear element as linear:
a) Simplicity of analysis and accuracy of results
b) Ease of calculations
c) Less time consuming
d) Mathematical tool available

Answer: d

3. A non-linear element can be treated as the linear element.
a) True
b) False

Answer: a

4. The system with the open loop transfer function 1/s(1+s) is:
a) Type 2 and order 1
b) Type 1 and order 1
c) Type 0 and order 0
d) Type 1 and order 2

Answer: d

5. The identical first order system have been cascaded non-interactively. The unit step response of the systems will be:
a) Overdamped
b) Underdamped
c) Undamped
d) Critically damped

Answer: d
6. A third order system is approximated to an equivalent second order system. The rise time of this approximated lower order system will be:
a) Same as the original system for any input
b) Smaller than the original system for any input
c) Larger than the original system for any input
d) Larger or smaller depending on the input

Answer: b

7. A system has a single pole at origin. Its impulse response will be:
a) Constant
b) Ramp
c) Decaying exponential
d) Oscillatory

Answer: a
28. When the period of the observation is large, the type of the error will be:
a) Transient error
b) Steady state error
c) Half-power error
d) Position error constant

Answer: b
9. When the unit step response of a unity feedback control system having forward path transfer function G (s) =80/s(s+18)?
a) Overdamped
b) Critically damped
c) Under damped
d) Un Damped oscillatory

Answer: a
10. With negative feedback in a closed loop control system, the system sensitivity to parameter variation:
a) Increases
b) Decreases
c) Becomes zero
d) Becomes infinite

Answer: b

CONTROL SYSTEM MCQs SET 24

Electronics Engineering February 13, 2020

CONTROL SYSTEM MCQs SET 24

CONTROL SYSTEM MCQs SET 24

1. In an automatic control system which of the following elements is not used?
a) Error detector
b) Final control element
c) Sensor
d) Oscillator

Answer: d
2. In a control system the output of the controller is given to
a) Final control element
b) Amplifier
c) Comparator
d) Sensor

Answer: a
3. A controller, essentially, is a
a) Sensor
b) Clipper
c) Comparator
d) Amplifier

Answer: c

4. Which of the following is the input to a controller?
a) Servo signal
b) Desired variable value
c) Error signal
d) Sensed signal

Answer: c

5. The on-off controller is a _____ system.
a) Digital
b) Linear
c) Non-linear
d) Discontinuous

Answer: d

6. The capacitance, in force-current analogy, is analogous to
a) Momentum
b) Velocity
c) Displacement
d) Mass

Answer: d
7. The temperature, under thermal and electrical system analogy, is considered analogous to
a) Voltage
b) Current
c) Capacitance
d) Charge

Answer: a

8. In electrical-pneumatic system analogy the current is considered analogous to
a) Velocity
b) Pressure
c) Air flow
d) Air flow rate

Answer: d

9. The use of feedback element in the feedback loop is:
a) It converts the output variable ‘c’ to another suitable feedback variable ‘b’ to compare with the input command signal.
b) It is the actuating element
c) To increase the stability
d) None of the mentioned

Answer: a

10. The major components of a controller are:
a) Control element
b) Error detector and control element
c) Feedback element
d) Error detector and feedback element

Answer: b

CONTROL SYSTEM SET 23

Electronics Engineering February 13, 2020

CONTROL SYSTEM SET 23

CONTROL SYSTEM SET 23

1. The effect of adding feedback makes the system__________
a) Linear
b) Non-linear
c) Time variant
d) Time invariant

Answer: a

2. The relation between output response and input signal in closed loop system is:
a) Exponential
b) Parabolic
c) Linear
d) Nonlinear

Answer: c

3. Assertion (A): Practical systems must be closed loop system.
Reason (R): This is due to the fact that closed loop systems are least affected by parameter variations, stable, higher bandwidth, linear and more speed of response.
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 true.

Answer: a

4. Regenerative feedback is also called as_________________
a) Negative feedback
b) Positive feedback
c) No feedback
d) Negative and Positive Feedback

Answer: b

5. Which of the following are the characteristics of regenerative feedback:
a) Zero damping
b) Stable
c) Least sensitive to parameter variations
d) None of the mentioned

Answer: a

6. Which of the following are true:
a) Sensitivity of regenerative feedback is more than negative feedback but less than non-feedback system
b) Sensitivity of regenerative feedback is more non-feedback system but less than negative feedback system
c) Sensitivity of regenerative feedback is less than both
d) Sensitivity of regenerative feedback is more than both

Answer: c

7. Loop gain provided by the regenerative feedback makes the closed loop transfer function insensitive to G(s).
a) True
b) False

Answer: a

8. Which of the following statements is correct for any closed loop system?
a) All the co-efficient can have zero value
b) All the co-efficient are always non-zero
c) Only one of the static error co-efficient has a finite non-zero value
d) None of the mentioned

Answer: c

9. Due to which of the following reasons excessive band width in control systems should be avoided?
a) It leads to slow speed of response
b) It leads to low relative stability
c) Noise is proportional to bandwidth
d) Presence of feedback

Answer: c

10. In a stable control system backlash can cause which of the following?
a) Underdamping
b) Overdamping
c) Poor stability at reduced values of open loop gain
d) Low-level oscillations

Answer: d

Saturday, February 8, 2020

CONTROL SYSTEM SET 22

Electronics Engineering February 08, 2020

CONTROL SYSTEM SET 22

CONTROL SYSTEM SET 22

1. For relative stability of the system which of the following is sufficient?
a) Gain margin
b) Phase margin
c) Both (a) and (b)
d) None of these

Ans: (c)

2. Slope in Bode plot is expressed as
a) – 6 db/decade
b) – 6 db/octave
c) – 7 db/octave
d) – 8 db/octave

Ans: (b)

3. Polar plots for+ve and –ve frequencies
a) Are always symmetrical
b) Can never be symmetrical
c) May be symmetrical
d) None of these

Ans: (a)

4. Gain margin of a first or second order system is
a) Zero
b) 100
c) 1
d) Infinity

Ans: (d)

5. Frequency range over which response of the system is within acceptable limits is called system
a) Modulation frequency
b) Demodulation frequency
c) Carrier frequency
d) Band width

Ans: (d)

6. By adding a pole at s = 0, Nyquist plot of the system will
a) Shift 90° clockwise
b) Shift 90° anticlockwise
c) Shift 180°
d) Not change at all

Ans: (a)

7. A complex-conjugate pair of poles near the jw axis will produce a
a) High oscillatory mode of transient response
b) Steady state mode of response
c) Sinusoidal mode of response
d) None of these

Ans: (a)

CONTROL SYSTEM SET 21

Electronics Engineering February 08, 2020

CONTROL SYSTEM SET 21

CONTROL SYSTEM SET 21

1. Bode analysis method can be applied
a) If transfer function has no poles and zeros on R.H. of s-plane
b) If transfer function has no poles on R.H. of s-plane
c) If transfer function has no zero on R.H. of s-plane
d) To all transfer functions
Ans: (a)

2. In a root locus plot, increase in 𝓴 will
a) Result in decrease in the damped and undamped natural frequencies
b) Result in increase in the damped and undamped natural frequencies
c) Not change the damped and undamped natural frequencies
d) None of these
Ans: (b)

3. Cut off is the slope of log-magnitude curve
a) At the start of curve
b) At the end of curve
c) Near the cut off frequency
d) None of these
Ans: (c)

4. Gain margin expressed in decibels is
a) Positive if Kg greater than 1 and negative for Kg less than 1
b) Negative if Kg greater than 1 and negative for Kg less than 1
c) Always zero
d) Infinity for Kg equal to 1
Ans: (a)

5. Bandwidth gives an indication of
a) Characteristic equation of the system
b) Speed of response of a control system
c) Transfer function of the control system
d) Transients in the system
Ans: (b)

6. Nyquist stability criterion requires polar plot of
a) Characteristic equation
b) Closed loop transfer function
c) Open loop transfer function
d) None of these
Ans: (c)

7. Cut off frequency is the frequency at which magnitude of closed loop frequency response is
a) 1 db below its zero frequency
b) 2 db below its zero frequency
c) 3 db below its zero frequency
d) 4 db below its zero frequency
Ans: (c)

8. In Nyquist criterion roots of the characteristic equation are given by
a) Zeros of open loop transfer function
b) Zeros of closed loop transfer function
c) Poles of closed loop transfer function
d) Poles of open loop transfer function
Ans: (c)

9. For all frequencies, a unit circle in the Nyquist plot transformer into
a) Db line of amplitude plot in Bode diagram
b) 1 db line of amplitude plot in Bode diagram
c) Either (a) and (b)
d) None of these
Ans: (c)

10. Transfer founction, when the bode diagram is plotted should be of the form
a) (1+T)
b) (1+S)
c) (Ts)
d) (1+Ts)
Ans: (d)

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