444 Control System Questions and Answers

Explore 444+ Control System questions and answers covering control theory, feedback systems, transfer functions, stability analysis, controllers, system modeling, and industrial control applications.

This collection includes technical questions related to:

Open Loop Control Systems
Closed Loop Control Systems
Transfer Functions
Block Diagram Reduction
Signal Flow Graphs
Time Response Analysis
Frequency Response Analysis
Stability Analysis
Root Locus Techniques
Bode Plots
Nyquist Plots
PID Controllers
Process Control Systems
Industrial Control Applications

The questions cover control system fundamentals, mathematical modeling, system dynamics, controller design, performance analysis, stability criteria, process control concepts, and practical engineering applications commonly used in electrical, electronics, instrumentation, and automation engineering.

These Control System questions are useful for engineering students, diploma holders, competitive exam aspirants, automation engineers, instrumentation professionals, and engineers preparing for technical interviews and academic examinations.

Browse the Control System questions below and strengthen your understanding of control engineering principles and industrial control technologies.

444 Control System Questions

S.No.	Control System Question
1	A gyroscope works on which of the following principles?
2	The input to a stepper motor is in the ___
3	For a two-phase servomotor which of the following statements is incorrect?
4	In root locus plot different roots have the ___
5	In pneumatic systems the medium used is ___
6	Which of the following is the non-linear system?
7	Which of the following is the output of a synchor error detector?
8	Gain margin is the factor by which the gain of the system is ___
9	Which of the following happens as the type of a system increases?
10	In amplidyne the compensating winding is ___
11	The damping ratio of the system having only two poles, each having a ___
12	The proportional error device has output as function of ___
13	The value of the resonant peak, in second order control system, will ‘be unity when ___
14	The servomechanisms with step displacement input is ___
15	By which of the following is the order of the system determined?
16	The operational amplifier used in servo amplification should have ___
17	If a step function is applied to the input of a system and ___
18	Which of the following is an advantage of Laplace transform method?
19	___ is not a form of non-linearity for a control system ___
20	A transfer function may be best defined as ___
21	___ is the reference input minus the primary feedback
22	___ is not a form of non-linearity for a control system
23	The viscous friction co-efficient, in force-voltage analogy, is ___
24	In an automatic control system which of the following elements is not used?
25	A phase lag lead network introduces in the ___
26	Which of the following should be done to make an unstable system stable?
27	The initial response when tne output is not equal to input is called ___
28	Velocity error constant of a system is measured when the input to ___
29	Spring constant in force-voltage analogy is ___
30	In electrical-pneumatic system analogy the current is considered analogous to ___
31	A control system with excessive noise, is likely to ___
32	___ is a closed loop system
33	A good control system has all the following features except ___
34	Which of the one is incorrect?
35	In a system the friction co-efficient is decreased to ___
36	Phase lag network does which of the following?
37	The overshoot (an indication of the largest error between the actual and desired output) is the ratio of ___
38	___ system provides excellent transient as well as steady-state response
39	On which of the following factors does the resolution of a potentiometer depend?
40	___ has infinite resolution
41	In type-1 system a constant output velocity at steady state will be ___
42	In a control system, noise can be reduced by ___
43	By the use of which of the following the power amplification of a magnetic amplifier is increased?
44	The eigen values of a linear system are the locations of ___
45	In pneumatic control system the output of ___
46	In a system of controlling oil flow to burner which of the following elements is not required?
47	For servomechanisms which of the following statements is incorrect?
48	The type 2 system has which of the following?
49	The system response can be tested better with ___
50	In a control application the choice of error detector depends on ___
51	A unit step function on integration results in a ___
52	The break away points of the root locus occur at ___
53	Through which of the following the frequency domain analysis can be related to time doniain analysis?
54	In hydraulic system power is transmitted by ___
55	The operational amplifier is used for which of the following?
56	Which of the following is an essential feature of servomechanism?
57	A servomechanism with unit step input can be ___
58	Bandwidth is used as a means of specifying performance of ___
59	With feed back ___
60	The phase lag produced by transportation relays ___
61	Hydraulic torque transmission system is analog of ___
62	The temperature, under thermal and electrical system analogy, is ___
63	Which of the following statements is correct for a system with ___
64	___ has tendency to oscillate
65	For transistor amplifier circuits the common emitter configuration is ___
66	A minor loop feedback compensation increases the steady state error by ___
67	The term confirmity is associated with which of the following?
68	With the knowledge of state space representation the transfer function of ___
69	Which of the following methods may be used to minimize the loading in potentiometers?
70	An ideal transformer should have ___
71	A synchro is employed ___
72	A ‘drag cup’ type motor has which of the following?
73	In a system nonlinearity may be introduced by which of the following?
74	___ can measure pressure error
75	In pneumatic instrumentation systems the pressure of ___
76	The root loci of a system has three asymptotes the system can ___
77	The frequency range is specified by which of the following?
78	If the bandwidth of a system is increased the response will ___
79	Which of the following forces resists motion?
80	The root locus plot is symmetrical about the ___
81	The maximum overshoot of a second order system can be increased by
82	Regenerative feedback means the output is ___
83	Which of the following devices is used to indicate angular position of an aircraft?
84	A servomechanism is a feedback control system required to ___
85	Type 1 system under parabolic input will have which of the following?
86	The lead compensator in a ___
87	Which of the following is the output of a thermocouple?
88	In a control system integral error compensation ___
89	The effect of error damping is to ___
90	In order to increase the clamping of a badly underdampecl system which of ___
91	The type 2 system has ___
92	The capacitance, in force-current analogy, is analogous to ___
93	The output of a feedback control system must be a function of ___
94	There is a ____ between the two nodes of signal flow graph
95	Which of the following statements is incorrect in respect of closed loop control system?
96	For which of the following reasons nonlinearities are introduced?
97	High power amplification is achieved by the use of ___
98	Which of the following types of motor has printed windings?
99	For a linear transfer function of the variable the transfer function of ___
100	The resolution of potentiometer should be ___
101	Which of the following materials is used for making a stator of a synchro?
102	The velocity lag error in the type-1 system is ___
103	By use of which of the following the system damping factor can be reduced?
104	Zero percent porportional band means ___
105	A pneumatic amplifier ___
106	Which of the following statements is incorrect for root locus technique?
107	By which of the following the order of the system can be determined?
108	In radars the control systein used is ___
109	Nyquist criterion is used to find which of the following?
110	A servomechanism usually consist of ___
111	The Bode plot is used to analyse which of the following?
112	In order to decrease the time constant of the control system its ___
113	The value of a node in the signal flow graph is ___
114	LVDT is an ___
115	___ is preferred when a control signal is required
116	The steady state acceleration error for a ___
117	A limit switch is used to ___
118	The transfer function technique is considered as inadequate under which of ___
119	If the gain of the critical damped system is increased it will ___
120	The type 1 system has ___
121	The on-off controller is a ___
122	Regenerative feedback implies feedback with ___
123	A closed loop system is distinguished from open loop system by which of the following?
124	Which of the following statements is not nedessarily correct for open control system?
125	The feedback of the tachometer reduces the ___
126	For frequency domain analysis sinusoidal signals considered have ___
127	The magnetic properties of silicon steel crystal are ___
128	The characteristic equation of the second order of the system is ___
129	In a feedback amplifier, the ___
130	Error Constants of a system are ___
131	Control Systems are normally designed with ___
132	The impulse function is a derivative of ___
133	The ON-OFF controller is ___
134	Transfer function of the control system ___
135	The transfer function has the main application in the study of ___
136	The transfer function of a system is ___
137	The Transfer function of the system is used to ___
138	In a hybrid feedback control systems carrier signals ___
139	Regenerative feedback ___
140	The transient response of a system is ___
141	The deviation of the primary feedback signal from the ___
142	In a control system, the controller output is ___
143	A controller essentially is ___
144	In a control system the use of ___
145	A control system in which control action depends on the output is ___
146	Introduction of the feedback reduces the ___
147	A Closed loop system is basically different from ___
148	In a control system the comparator compares the output response and ___
149	The weighting function of the control system is ___
150	A signal other than the reference input that tends to affect the value of controlled variable is ___
151	In a control system the comparator measures the ___
152	Tachometer is employed to ___
153	Potentiometers are used in ___
154	The thermocouple directly converts temperature ___
155	The input to a controller is always a/an ___
156	Synchros are widely used for transmission of ___
157	___ can be used for converting the angular the angular position of a shaft
158	The output of synchro error detector is ___
159	AC Servo motor is basically a ___
160	A gyroscope operates on the ___
161	Which of the following is not true for ___
162	Two stator windings of the ac servo motors are oriented ___
163	Bimetallic thermostat is ___
164	Transfer function of a control system ___
165	The transfer function of a system is used to ___
166	Laplace transform method has the ___
167	A transfer function of a system is a Laplace transform of ___
168	The basic property of the signal flow graph is ___
169	A signal flow graph is ___
170	___ gives indication how fast the system tends to attain the final value
171	Error constants of the system are measure of ___
172	The overshoot (an indication of the largest error between the actual and desired output) is ___
173	A signal whose value changes from one level to ___
174	Control systems are normally designed with a ___
175	The time required for the response to rise from 10% to 90% of the ___
176	The required for the response to rise and stay within the ___
177	An impulse function is a derivative of ___
178	A unit step function on integration results ___
179	In a control system noise can be ___
180	Transient function of the system and the response in terms of ___
181	Differentiators are avoided in the system design as ___
182	The second derivative input signal ___
183	Transfer function can be obtained from ___
184	Velocity error constant of the system is a measured when the input of the ___
185	The steady state error of a control system can be ___
186	In a PID controller, the overshoots has ___
187	In a PID controller, the offset has increased ___
188	Which of the following system provides excellent transient and ___
189	The number of operational amplifiers require for designing of ___
190	When derivative action is included in a proportional controller, the ___
191	In a proportional temperature controller, if the quantity under the ___
192	The integral control ___
193	The term reset control refers to ___
194	Proportional band of the controller is ___
195	Proportional band of a controller is defined as the ___
196	Which of the following is exhibited by Root locus diagrams?
197	The first order control system, which is well designed, has a ___
198	A.C. servomotor is basically a ___
199	The transfer function technique is considered as inadequate under which of the following conditions?
200	___ directly converts temperature into voltage
201	Which of the following can be measured by LVDT?
202	An amplidyne can give which of the following characteristics?
203	With feed back _____ reduces
204	In a control system integral error compensation _______ steady state error
205	If the gain of the critical damped system is increased it will behave as ___
206	Which of the following is an electromechanical device?
207	When the initial conditions of a system are specified to be zero it implies ___
208	___ can be extended to systems which are time-varying?
209	Which of the following is the non-linearity caused by servomotor?
210	___ technique gives quick transient and stability response
211	Which of the following devices is used for conversion of co-ordinates?
212	Pressure error can be measured by which of the following?
213	Which of the following is the definition of proportional band of a controller?
214	___ is not a final control element
215	Which of the following can be measured by the use of a tacho-generator?
216	In a stable control system saturation can cause which of the following?
217	In order to increase the damping of a badly underdamped system which of following compensators may be used?
218	___ technique is not applicable to nonlinear system?
219	Addition of zeros in transfer function causes which of the following?
220	Phase margin of a system is used to specify which of the following?
221	Which of the following is the best method for determining the stability and transient response?
222	If a step function is applied to the input of a system and the output remains below a certain level for ___
223	In case of type-1 system steady state acceleration is ___
224	Velocity error constant of a system is measured when the input to the system is unit _______
225	The position and velocity errors of a type-2 system are ___
226	The type 2 system has at the origin ___
227	The type 1 system has ______ at the origin
228	The type 0 system has ______ at the origin
229	In a hybrid feedback control system carrier signals are ___
230	Synchros’ are popularly used as ___
231	A system which has some roots with real parts equal to ___
232	As compared to a potentiometer which of the following is high for a LVDT?
233	The servomotor differs from other motors in the ___
234	Which of the following is the disadcantage of hydraulic system over electrical system?
235	___ is prefered for self-balancing instruments?
236	Magnetic amplifiers are used to amplify which of the following?
237	A controller is basically a ___
238	The state-variable representation is ___
239	As compared to electronic systems which of the following is ___
240	The input to a controller is ___
241	The effect of error rate damping is ___
242	If the clamping factor of a control system is unity it ___
243	___ will increase the steady state accuracy?
244	For a D.C. generator input could be in ___
245	The magnitude of system output, for ___
246	When damping factor decreases the ___
247	A signal flow graph is a ___
248	Selsyn’ is the trade name given to ___
249	The servosystem with step acceleration input is ___
250	Diodes are connected in series with A.C. source of the magnetic amplifier mainly to ___
251	In case of an on-off controller the proportional band is ___
252	A differentiator is usually not a part of a control system because it ___
253	The type 0 system has ___
254	Mass, in force-voltage analogy, is ___
255	Which of the following is the input to a controller?
256	The transient response, with feedback system ___
257	As a result of introduction of negative feedback which of the following will not decrease?
258	Any externally introduced signal affecting the controlled output is ___
259	In signal flow graph function points are ___
260	Type 0 system has ___
261	In a non-linear control system limit cycle is self sustained oscillations of ___
262	Because of which of the following the use of deposited film type potentiometer is ___
263	If the complex poles of a system have greater real parts, them overshoot is ___
264	Steep out off characteristics will have ___
265	The effect of adding potes and zeros can be determined quickly by which of the following?
266	A reduction gear is used to increase the ___
267	By which of the following methods steady state error can be minimized?
268	A servo system will become absolutely unstable if ___
269	___ cannot be the final control element
270	The compressed air in pneumatic control systems is ___
271	The transfer function of a system can be used to ___
272	Synchros’ are commonly used as transmitters of ___
273	At which of the following root loci will end?
274	___ is the non-linearity caused by servomotor
275	Which of the following is an advantage of Bode plot?
276	Transfer function technique is inadequate when the ___
277	In a control system an ___
278	In several applications hydraulic motors are preferred to ___
279	For root locus technique which of the following statements is incorrect?
280	In pneumatic control systems the control valve used as___
281	A conditionally stable system exhibits poor stability at ___
282	With feedback ___
283	On which of the following factors does the sensitivity of a closed loop system to ___
284	A.C. servo Motor resembles ___
285	An automatic toaster is ___
286	In closed loop control system, with positive value of feedback gain the ___
287	The gain of the amplidyne is related to the gain of D.C. generator of ___
288	LVDT is preferred over the potentiometer as an error detector because ___
289	Slope of asymptote in Bode plot for a second order system is ___
290	The Root locus are the plots of the variations of the poles of ___
291	Sampled data systems final application in which of the following?
292	Which of the following is an assumption made in Laplace technique in sampled data control?
293	The loading effect-on the potentiometer can be avoided by the use of ___
294	In aircrafts the use of hydraulic motor is preferred over the ___
295	Regulator can be categorized as ___
296	Frequency domain analysis is preferred when dealing with ___
297	In system design which of the following is the disadvantage of differentiators?
298	Which of the following is incorrect?
299	___ is used for Nyquist plot
300	The phase difference between the two windings of A.C. servomotor is ___
301	___ use hydraulic control devices?
302	In the case of a second order differential equation when ___
303	A.C. servomotor, as compared to a standard induction motor has ___
304	Which of the followin.g is a disadvantage of a series D.C. motor?
305	In a control system noise can be avoided by which of the following methods?
306	In pneumatic-electrical analogy, the electrical resistance is ___
307	In pneumetic systems a restrictionvolume combination is equivalent to ___
308	In pneumatic control systems compensation is provided by which of the following?
309	___ is the serious disadvantage of electronic control systems
310	Backlash, in a stable control system, can cause which of the following?
311	The gain margin is the factor by which the gain of the system can be ___
312	The output of a stepper motor is in the form of ___
313	For root loci which of the following are the starting points?
314	For system gain to be zero, the roots will move towards ___
315	Non-linearities can be ___
316	System damping can be increased by using compensator having pair of ___
317	When the gain margin is positive and the phase margin is negative, the system is ___
318	Phase margin is the amount of angle to make the ___
319	When synchro transmitter shaft is disconnected from the driving shaft it will ___
320	By the used of which of the following high power amplification is achieved?
321	Which of the following is the basic property of signal flaw graph?
322	The transfer function of a system is used calculate which of the following?
323	A zero order hold is used with sampled data system to ___
324	___ is the input which is established or varied by some means external to and independent of ___
325	In distributed systems the transportation delays are detrimental to stability due to which of the following reasons?
326	A servomotor entails which of the following disadvantages?
327	Proportional band of a controller is expressed as ___
328	When the initial conditions of a system are specified to be ___
329	Which of the followit’ig can be measured by LVDT?
330	Which of the following is the nonlinearity caused by servomotor?
331	Static error co-efficients are used as a measure of the effectiveness of ___
332	The term backlash is associated with ___
333	In a control system the output of the controller is ___
334	In liquid level and electrical system analogy, voltage is considered analogous to ___
335	___ increases the steady state accuracy
336	Zero initial condition for a system means ___
337	A control system working under unknown random actions is ___
338	A control system in which the control action is somehow dependent on the ___
339	A car is running at a constant speed of 50 km/h, which of the following is ___
340	Micros is a component based on the principle of ___
341	The frequency range specification required to satisfactorily describe the ___
342	Which of the following is the specification of optimal control problems?
343	To maximize or minimize a set of criteria is ___
344	Differential used in synchro differential unit indicates which of the following?
345	The steady state output of a unity feedback control system is ___
346	The effect of second derivative input control is ___
347	The Bode plot is applicable to ___
348	Which of the following is an example of intentional non-linear systems?
349	In a magnetic amplifier the purpose of bias winding is ___
350	Which of the following is an advantage of on line identification?
351	By which of the following methods viscous friction can be added to a servomechanism?
352	In a pneumatic control valve the function of valve positioner is ___
353	Which of the foaming is the main advantage of hydraulic system over electrical system?
354	In order to convert the angular position of a shaft into an ___
355	By which of the following methods the steady state error of a control system can be reduced?
356	Which of the following terms is not connected with potentiometer?
357	Electrical capacitance in pneumatic systems is ___
358	A servomechanism with step displacement input will ___
359	In a compressed air plant which of the following is not a function of the reservior?
360	Which of the following is the setting time in the second order linear system?
361	In pneumatic systems time lags are obtained by ___
362	The time required for the response to reach half the final value for ___
363	The overshoot is an indication of ___
364	Static error co-efficients are used as a measure of the effectiveness of closed loop systems ___
365	An increase in gain, in most systems, leads to ___
366	The frequency and time domain are related through which of the following?
367	Spring constant in force-voltage analogy is analogous to ___
368	In a system low friction co-efficient facilitates ___
369	In a system zero initial condition means that ___
370	By which of the following the system response can be tested better?
371	With feedback _____ increases
372	From which of the following transfer function can be obtained?
373	The transfer function is applicable to which of the following?
374	A signal other than the reference input that tends to affect the value of ___
375	___ signal will become zero when the feedback signal and reference signs are equal
376	The transient response of a system is mainly due to ___
377	Mass, in force-voltage analogy, is analogous to ___
378	In thermal-electrical analogy charge is considered analogous to ___
379	In force-voltage analogy, velocity is analogous to ___
380	The viscous friction co-efficient, in force-voltage analogy, is analogous to ___
381	In a stable control system backlash can cause which of the following?
382	Due to which of the following reasons excessive bond width in control systems should be avoided?
383	Which of the following statements is correct for a system with gain margin close to unity or a phase margin close to zero?
384	Which of the following statements is correct for any closed loop system?
385	The second derivative input signals modify which of the following?
386	On which of the following factors does the sensitivity of a closed loop system to gain changes and load disturbances depend?
387	Transfer function of a system is used to calculate which of the following?
388	___ is an open loop control system
389	Which of the following devices are commonly used as error detectors in instruments?
390	By which of the following the control action is determined when a man walks along a path?
391	___ is a part of the human temperature control system
392	An automatic toaster is a ______ loop control system
393	A car is running at a constant speed of 50 km/h, which of the following is the ___
394	In open loop system ___
395	Which of the following statements is not necessarily correct for open control system?
396	Which of the following is an open loop control system?
397	A control system in which the control action is somehow dependent on the output is ___
398	For open control system which of the following statements is incorrect?
399	In an open loop control system ___
400	If any term in the first column of a Routh array becomes zero, then ___
401	Temperature is analogous to ___
402	Which of the following is used to obtain output position in a position control system?
403	Which dc servomotor requires strongest permanent magnet?
404	A conditionally stable system is stable for the value of gain between ___
405	DC tachogenerator can be used in ___
406	The addition of a pole to the open loop transfer function pulls the ___
407	For any transfer function, the constant phase angle loci are ___
408	The permanent magnet field system of brushless dc servo- motor is ___
409	The distance of poles from origin depends on ___
410	Which of the following is correct?
411	Bandwidth is proportional to speed of response ___
412	In a simple on-off controller with differential gap, the magnitude of ___
413	If poles lie in first quadrant, damping ratio is ___
414	If the poles lie in second quadrant, damping ratio is ___
415	In force current analogy, displacement x is analogous to ___
416	Nyquist stability criterion uses open loop frequency response characteristics ___
417	Which control action can never be used alone?
418	Magnetic amplifier is used for ___
419	Nichols chart consists of ___
420	In force current analogue, mechanical mobility is analogous to ___
421	The sensor generally used in incremental optical encoder is ___
422	The poles with greater displacement from the real axis correspond to ___
423	Which of the following is open loop system?
424	In a two phasor servomotor, the direction of rotation of the rotating field depends on ___
425	A system is highly oscillatory if ___
426	M circles are symmetrical with respect to ___
427	In control systems the output of sensor usually, is ___
428	Which of the following can be used as a rotating amplifier in a control system?
429	The effect of adding poles and zeros can be determined quickly by ___
430	For type 1 system the velocity lag error is ___
431	Gain margin and phase margin can be determined from ___
432	Integral control action ___
433	In Bode plots the frequency at which two asymptotes meet is called ___
434	In the field controlled motor the entire damping comes from ___
435	For a stable system having two or more gain crossover frequencies the phase margin is ___
436	Nichol’s chart is symmetric about-180° axis ___
437	Transport lag usually exists in ___
438	The relative stability of a system is given by ___
439	A lead compensator ___
440	Which of the following features is not associated with Nichols chart?
441	The complicated shapes in the polar plots are only due to time constants in the numerator of ___
442	Lag compensation permits a high gain at ___
443	In root locus analysis the breakaway and break in points ___
444	About the Control System MCQ category