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IC 6501 :CONTROL SYSTEMS MULTIPLE CHOICE QUESTIONS (MCQ) UNIT I –(SYSTEMS – (SYSTEMS AND THEIR REPRESENTA R EPRESENTATION) TION)
1. Which system is also known as automatic control system? a) open loop control system b) closed loop control control system c) either 1 or 2 d) nether 1 nor 2 Answer : b 2. Advantages of open loop system isare? a) simple and economical b) accurate c) reliable d) all of the above Answer : a !. Which of the following are the disadvantages of a closed loop control system? a) reduces the overall gain b) comple" and costly c) oscillatory response d) all of the above Answer : d #. $he output of the system has an effect upon the input %uantity& %uantity& then the s ystem is a a) open loop control system b) closed loop control control system c) either 1 or 2 d) none of the above Answer : b '. (y using which of the following elements& mechanical translational systems systems are obtained? a) mass element b) spring element c) dashpot d) all of the above Answer : d *. +orce balancing e%uation of a mass elements is , where " - displacement) a) d/"dt/ b) d"dt c) 0" d) any of the above Answer: a . Which of the following isare the advantages of a closed loop control system? a) $he closed loop systems are accurate b) $he closed loop loop systems are less affected affected by noise
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c) both 1 and 2 d) neither 1 nor 2 Answer : c . 3f a circuit consisting of two mass elements& two spring elements and four friction elements. +ind the order of transfer function? a) 2 b) # c) * d) 12 Answer : b 4. 3f two blocks having gains A and ( respectively are in series connection& find the resultant gain using block diagram reduction reduction techni%ue? a) A5( b) A0( A0( c) A( d) A( Answer : b 16. 3f two blocks having gains A and ( respectively are in parallel connection& find the resultant gain using block diagram reduction techni%ue? a) A5( b) A0( A0( c) A( d) 2,A5() Answer : a 11. +or the block diagram given in the following figure& the e"pression of 78 is:
a) 91929!19291 b) 9192191929! 9192191929! c) 91929!191929! 91929!191929! d) 91929!,19192) 91929!,19192) Answer: a 12. $he transfer function from ,s) to ;,s) is :
a) 2!s5 b) 2!s51
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c) *!s5 d) 2!s5* Answer: a 1!. $he closed loop gain of the s ystem shown in the given figure is :
a) 4' b) *' c) *' d) 4' Answer: b 1#. $he advantage of block diagram representation is that it is possible to evaluate the contribution of each component to the overall performance of the system. a) $rue b) +alse Answer: a 1'. $he overall transfer function from block diagram reduction for cascaded blocks is : a) aplace output to >aplace input considering initial conditions a) 1 b) 2 c) 6 d) infinite Answer: c 1. 3n the following block diagram& 91-16s 92-16s51 1-s5!& 2-1. $he overall transfer function is given by :
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a. 1611s25!1s516 b. 16611s25!1s5166 16611s25!1s5166 c. 16611s25!1s516 d. 16611s25!1s Answer: b 14. @scillations in output response is due to : a. =ositive feedback b. egative feedback c. o feedback d. one of the mentioned Answer: a UNIT-2 UNIT-2 (TIME RESPONSE ANALYSIS) ANALYSIS)
1. $he steady state error for a unity feedback system for the input r,t) - 8tB22 to the system 9,s) C,s52)s,s!5s2512s) C,s52)s,s!5s2512s) is a) 6 b) *8C c) D d) !8C Answer: b 2. A control system is operated with a parabolic input as shown below
3f Ca is static error constant of the system& then its dynamic error constant C2 is a) 6.61 b) 6.62 c) 6.6! d) 6.6# Answer: b !. +ind the velocity error constant of the system given below :
a) 6 b) 2
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c) # d) D Answer: c #. 7onsider the unity feedback system with open loop transfer function the minimum value of the steady state error to a ramp input r,t) - *tu,t) is @>$+ - Cs,s51),s52) a) 1 b) 2 c) ! d) # Answer: b '. A ramp input input applied to a unity feedback system results in 'E steady state error. $he type number and Fero fre%uency gain of the system s ystem are respectively a) 1 and 26 b) 6 and 26 c) 6 and 126 d) 1 and 126 Answer: a *. A particular particular control system yielded a steady state error of 6.26 for unit step input. A unit integrator integrator is cascaded to this system and unit ramp input is applied to this modified system. What is the value of steadystate error for this modified system? a) 6.16 b) 6.1' c) 6.26 d) 6.2' Answer: d . $he error constants described are the ability to reduce the steady state errors. a) $rue b) +alse Answer: a .
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16. $he disadvantages of the error constants are: a. $hey do not give the information of the steady state error when the inputs are other than the three basic types b. Grror constant fail to indicate indicate the e"act manner in which which the error function change with time. c. $hey do not give information of the steady state error and fail to indicate the e"act manner in which the error function change with time d. $hey give information of the steady state error Answer: c 11. What is the type of closed loop system for the plant transfer function 9,s) - ks/,15$s) ks/,15$s) and with unity feedback? a) 1 b) ! c) 2 d) 6 Answer: c 12. Which of the following statement isare true statements? a) $ype $ype of the system is obtained from open loop transfer function b) $he steady state state analysis depends on type of the system c) $ransient state analysis analysis depends on order of the system d) all of the above Answer: d 1!. What is the order of closed loop system for the plant transfer function 9,s) - ks/,15$s) ks/,15$s) and with unity feedback a) ! b) 2 c) 1 d) 6 Answer: a 1#. A second second order control system is defined by the following e%uation: # d/c,t)dt/ 5 dc,t)dt 5 1* c,t) - 1* u,t) $he damping ratio and natural fre%uency for this system are respectively a) 6.2' and 2 rads b) 6.2' and # rads c) 6.'6 and 2 rads d) 6.'6 and # rads Answer: c 1'. $he steady state error due to ramp input for a t ype two system is e%ual to a) Hero b) 3nfinite c) non Fero number d) constant Answer: a 1*. ifferentiation of parabolic response is a response? a) =arabolic b) 8amp
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c)
Answer: a 2.
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a) Asymptotic plots b) =olar plots c) 8oot locus techni%ue d) 7onstant and n circle Answer: c !.
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Answer: d 4. 7onstant loci: a) 7onstant gain and constant phase shift loci of the closedloop system. b) =lot of loop gain with with the variation in fre%uency fre%uency c) 7ircles of constant gain for the closed loop transfer function d) 7ircles of constant phase shift for the closed loop transfer function Answer: c 16. icholLs chart: a) 7onstant gain and constant phase shift loci of the closedloop system. b) =lot of loop gain with with the variation in fre%uency fre%uency c) 7ircles of constant gain for the closed loop transfer function d) 7ircles of constant phase shift for the closed loop transfer function Answer: b 11. Assertion Assertion ,A): 8elative stability of the system reduces due to the presence of transportation lag. 8eason ,8): $ransportation lag can be conveniently handled by (ode plot. a) (oth A and 8 are true but 8 is correct e"planation of A b) (oth A and 8 are true but 8 is correct e"planation e"planation of A c) A is true but 8 is false d) A is false but 8 is true Answer: b 12. Assertion Assertion ,A): $he phase angle plot in (ode diagram is not affected by the variation in the gain of the system. 8eason,8): $he variation in the gain of the s ystem has no effect on the phase margin of the system. a) (oth A and 8 are true but 8 is correct e"planation of A b) (oth A and 8 are true but 8 is correct e"planation e"planation of A c) A is true but 8 is false d) A is false but 8 is true Answer: c 1!. A system system has poles at 6.61 F& 1 F and 6F& Feroes at 'F& 166F and 266F. $he appro"imate phase of the system response response at 26 F is : a) 46M b) 6M c) 46M d) 16M Answer: a 1#. $he constant circle represented by the e%uation "B252.2'"5yB2-1.2' has the value of e%ual to: a) 1 b) 2 c) ! d) #
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Answer: c 1'. What is the value of for the constant circle represented by the e%uation "B251"5yB254-6? "B251"5yB254-6? a) 6.' b) 2 c) ! d) Answer: c 1*. $he constant loci represented by the e%uation "B25"5yB2-6 is for the value of phase angle e%ual to: a) #'M b) 6M c) #'M d) 46M Answer: d 1. All the constant circles in 9 planes cross the real a"is at the fi"ed points. Which are these points? a) 1 and origin b) @rigin and 51 c) 6.' and 6.' d) 1 and 51 Answer: a 1. 7onsider the following statements: icholLs icholLs chart gives information information about. i. 7losed loop fre%uency response. ii. $he value of the peak magnitude of the closed loop fre%uency response p. iii. $he fre%uency at which p occurs. Which of the above statements are correct? a) 2 and ! b) 1 and 2 c) 1 and ! d) 1&2 and ! Answer: d 14. Which one of the following statements is correct? icholLs chart is useful for the detailed study analysis of: a) 7losed loop fre%uency response b) @pen loop fre%uency response response c) 7lose loop and open loop fre%uency responses d) one of the above Answer: a 26. 3n a bode magnitude plot& which one of the following slopes would be e"hibited at high fre%uencies by a #th order allpole allpole system? a) 6d(decade b) #6 d(decade
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c) #6 d(decade d) 6 d(decade Answer: a 21. +re%uency range of bode magnitude and phases are decided by : a) $he lowest and higher important fre%uencies of dominant factors of the @>$+ b) $he lowest and and highest important fre%uencies of all the factors factors of the open loop transfer transfer function c) 8esonant fre%uencies of the second factors d) one of the above Answer: d 22. @>$+ @>$+ contains one Fero in right half of splane then a) @pen loop system is unstable b) 7lose loop system is unstable c) 7lose loop system is unstable for higher gain d) 7lose loop system is stable Answer: c 2!. $he critical value of gain for a system is #6 and gain margin is *d(. $he system is operating at a gain of: a) 26 b) #6 c) 6 d) 126 Answer: a 2#. icholLs icholLs chart is useful for the detailed study and analysis of: a) 7losed loop fre%uency response b) @pen loop fre%uency response response c) 7lose loop and open loop fre%uency responses d) open loop and 7lose loop fre%uency responses Answer: a 2'. $he roots of the characteristic e%uation of the second order system in which real and imaginary part represents the : a) amped fre%uency and damping b) amping and damped fre%uency fre%uency c) atural fre%uency and damping ratio d) amping ratio and natural fre%uency Answer: b
2*. $he constant circle for -1 is the a) straight line "-12 b) critical point ,1J6) ,1J6) c) circle with r- 6.!! d) circle with r-6.*
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Answer: a 2. $he polar plot of a transfer function passes through the critical point ,1&6). 9ain margin is a) Hero b) 1d( c) 1d( d) 3nfinity Answer: a 2. 7onsider the following statements: 1. $he effect of feedback is to reduce the system error 2. +eedback increases the gain of the system in one fre%uency range but decreases in another !. +eedback can cause a system that is originally stable to become unstable Which of these statements are correct. a) 1&2 and ! b) 1 and 2 c) 2 and ! d) 1 and ! Answer: c 24. $he open loop transfer function of a system is 9,s) ,s)- C ,15s),152s),15!s) $he phase cross over fre%uency Nc is a) O2 b) 1 c) Hero d) O! Answer: b !6. 3f the gain of the openloop system is doubled& the gain margin a) 3s not affected b) 9ets doubled c) (ecomes half d) (ecomes onefourth Answer: a !1. $he unit circle of the y%uist y%uist plot transforms into 6d( line of the amplitude plot of the (ode diagram at a) 6 fre%uency b) >ow fre%uency c) igh fre%uency d) Any fre%uency Answer: d !2. 7onsider the following statements: $he gain margin and phase margin of an unstable system ma y respectively be
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1. =ositive& positive 2. =ositive& negative !. egative& positive #. egative& negative @f these statements a) 1 and # are correct b) 1 and 2 are correct c) 1& 2 and ! are correct d) 2&! and # are correct Answer: d !!. 3f a system has an open loop transfer function 1s 15s& then the gain of the system at fre%uency of 1 rads will be a) 1 b) 12 c) Hero d) 1 Answer: d !#. $he polar plot of the open loop transfer function of a feedback control system intersects the real a"is at 2. $he gain margin of the system is a) 'd( b) 6d( c) *d( d) #6d( Answer: c !'. +or the transfer function 9,s) ,s) - 1 s,s51) ,s56.')& the phase crossover fre%uency is a) 6.' radsec b) 6.6 radsec c) 1.!2 radsec d) 2 radsec Answer: b !*. $he gain margin ,in d() of a system having the loop transfer function 9,s) ,s) - 2 s,s51) is a) 6 b) ! c) * d) Answer: d !. $he gain margin for the system with open loop transfer function 9,s) ,s) - 9,s) -2,15s) s2 is a) b) 6
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c) 1 d) Answer: b !.
Answer: d 2. A linear time invariant system is stable if : a) inear
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Answer: c *. >inear mathematical model applies to : a) >inear systems b)
inear d)
inear d)
inear Answer: c 12. 3f the roots of the have negative real parts then the response is a)
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c) arginally stable d) (ounded Answer: d 1!. 3f root of the characteristic e%uation has positive real part the system is : a)
inear Answer: b 1#. A linear system can be classified as : a) Absolutely stable b) 7onditionally stable stable c) Pnstable d) All of the mentioned Answer: d 1'. RRRRRRRRRRR is a %uantitative measure of how fast the transients die out in the system. a) Absolutely stable b) 7onditionally stable stable c) Pnstable d) 8elative
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14. $he unit step response of the s ystem is 1 et,15t). Which is the system? a) Pnstable b)
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d) 3t gives gain& phase margin and number of roots lying in 8< of the splane Answer: d 2*. $he order of the au"iliary polynomial is always: a) Gven b) @dd c) ay be even or odd d) one of the mentioned Answer: a 2. Which of the test signals are best utiliFed by the stability analysis. a) 3mpulse b) inear Answer: c 24. $he characteristic e%uation of a system is given ass!52's2516s5'6-6. What is the number of the roots in the right half splane and the imaginary a"is respectively? a) 1&1 b) 6&6 c) 2&1 d) 1&2 Answer: b !6. 7onsider the following statement: a) A system system is said to be stable if its output is bounded for any input b) A system is said to be be stable if all the roots of the the characteristic e%uation e%uation lie on the left half half of the s plane. c) A system system is said to be stable if all the roots of the characteristic e%uation have negative real parts. d) A second second order system is always stable for finite values of open loop gain Answer: a !1. $he necessary condition for the stability of the linear system is that all the coefficients of characteristic e%uation 159,s),s) 159,s),s) -6& be real and have the : a) =ositive sign b) egative sign c)
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Answer: c !2. +or making an unstable system stable: a) 9ain of the system should be increased b) 9ain of the system should should be decreased c) $he number of Feroes to the loop transfer function should be increased d) $he number of poles to the loop transfer function should be increased Answer: b !!. 8oot locus of s,s52)5C,s5#) -6 is a circle. What are the coordinates of the center of this circle? a) 2&6 b) !&6 c) #&6 d) '&6 Answer: c !#. $he main obJective of drawing root locus plot is : a) $o $o obtain a clear picture about the open loop poles and Feroes of the system b) $o $o obtain a clear picture about about the transient response response of feedback system system for various values of open loop gain C c) $o determine sufficient condition condition for the value of UCL that will make the feedback s ystem unstable d) (oth b and c Answer: d !'. While increasing the value of gain C& the system becomes a) >ess stable b) ore stable c) Pnstable d) Absolute stable Answer: a !*. $he addition of open loop poles pulls the root locus towards: a) $he right and system becomes unstable b) 3maginary a"is and system system becomes marginally stable c) $he left and system becomes unstable d) $he right and system becomes unstable Answer: d !. 8oot locus is used to calculate: a) arginal stability b) Absolute Absolute stability c) 7onditional stability d) 8elative stability Answer: d
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!. 8outh urwitF criterion is better than root locus. a) $rue b) +alse Answer: b !4. 7onsider the following statements regarding r oot loci: a) All root loci start from the respective poles of 9,s) ,s) b) All All root loci end at the respective respective Feros of 9,s) ,s) or go to to infinity c) $he root loci are s ymmetrical about the imaginary a"is of the splane d) All root loci start and end from the respective poles of 9,s) ,s) or go to infinity Answer: b #6. umber of roots of characteristic e%uation is e%ual to the number of a) (ranches b) 8oot c)
UNIT-V (STATE VARIALE ANALYSIS) 1. $he transfer function for the state representation of the continuous time >$3 >$3 system: d%,t)dt-A%,t)5(",t) ;,t)-7%,t)5",t) is given by: a) 7,s3A)1(5 b) (,s3A)1(5 c) 7,s3A)1(5A d) ,s3A)1(57
Answer: a 2. $3 >$3 system e"pressed in state variable form with Fero initial condition a) 7,F3A)1(5 b) 7,F3A)1 c) ,F3A)1F d) ,F3A)1 Answer: a
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!. and then& a) V8 and > are both small b) V8 is large but > > is small c) V8 is small s mall but > is large d) V8 and > are both large Answer: c . 7onsider the following statements relating to synchroLs: synchroLs: 1. $he rotor of the control transformer is either disc shaped 2. $he rotor of the transmitter is so constructed as to have a low magnetic reluctance !. $ransmitter $ransmitter and control transformer pair is used as an error detector Which of these statements are correct? a) 1&2 and! b) 1 and 2 c) 2 and! d) 1 and ! Answer: c . Grror detector: a) Armature controlled += 7 motor b) A pair of synchronous transmitter and control control transformer c) $ach generator d) Amplidyne Answer: a
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4.
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Answer: b 1#. $he transfer function ;,s)P,s) of a system described by the state e%uations d"dt-2"52u and y,t) 6.'" is: a) 6.',s2) b) 1,s2) c) 6.',s52) d) 1,s52) Answer: d 1'. A linear time invariant single input single output system has the state space model given by
d"dt-+"59u& y-F& where input& and y is the output. $he damping ratio of the system is: a) 6.2' b) 6.' c) 1 d) 2 Answer: b
1*. 9iven the matri" a) 1&2&! b) 1 c) 1&2&! d) 6 Answer: c
. ere& " is the state vector& u is the
the Gigen value areRRRRRRRRRRR
1. A transfer function of control system does not have poleFero cancellation. Which one of the following statements is true? a)
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14. $he state e%uation in the phase canonical form can be obtained from the transfer function by: a) 7ascaded decomposition b) irect decomposition decomposition c) 3nverse decomposition d) =arallel decomposition decomposition Answer: d 26. A logarithmic logarithmic spiral e"tending out of the singular point isRRRRRRRRRR a)