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MCQOPTIONS
This section includes 519 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 151. |
The frequency at which magnitude of closed loop frequency response is 3 dB below its zero frequency value is called critical frequency. |
| A. | 1 |
| B. | |
| C. | 1 |
| D. | |
| Answer» C. 1 | |
| 152. |
Consider the following statements about variable reluctance stepper motor used in control system The static torque acting on rotor is a function of angular misalignment between stator and rotor teethThere are two positions of zero torque i.e, . Q = 0 and where T is the number of rotor teethBoth zero torque positions are stableWhen stator is excited, rotor is pulled into minimum reluctance position Of these statements, the correct ones are |
| A. | 2, 3, 4 |
| B. | 1, 2, 3 |
| C. | 1, 2, 4 |
| D. | 1, 3, 4 |
| Answer» D. 1, 3, 4 | |
| 153. |
In op-amp circuit of the given figure, Eo(s)/Ei(s) = |
| A. | |
| B. | |
| Answer» B. | |
| 154. |
In the given figure, the combinations of two non touching loops is |
| A. | 90° |
| B. | 180° |
| C. | 270° |
| D. | 360° |
| Answer» C. 270¬∞ | |
| 155. |
Which of the following features is not associated with Nichols chart? |
| A. | (0 dB, -180°) point on Nichols chart represent critical Point (-1, 0) |
| B. | It is symmetric about -180° |
| C. | M loci are centred about (0 dB, -180°) point |
| D. | The frequency at intersection of G(jω) locus and M = +3 dB locus gives bandwidth of closed loop system |
| Answer» E. | |
| 156. |
Frequency response approach is a simple approach to control system design. |
| A. | 1 |
| B. | |
| C. | non-minimum phase function |
| D. | minimum phase function |
| Answer» B. | |
| 157. |
Nichols chart consists of M and N locii in log magnitude versus phase diagram. |
| A. | 1 |
| B. | |
| C. | zero and 1 |
| D. | zero and 10 |
| Answer» B. | |
| 158. |
If phase angle of open loop transfer function becomes - 180° at frequency ω1, then gain margin is equal to |
| A. | |G(jω1)| |
| B. | |
| Answer» C. | |
| 159. |
A unity feedback system has the following open loop frequency responseThe gain margin and phase margin are |
| A. | 0 dB, 10° |
| B. | 3.86 dB, 10° |
| C. | stator |
| D. | rotor |
| Answer» E. | |
| 160. |
For a second order system damping factor is 0.1. If ωd is frequency of damped oscillations and ωn is natural frequency, then |
| A. | ωd ≈ ωn |
| B. | |
| C. | ωn ≈ ωn |
| Answer» B. | |
| 161. |
For an unstable system the gain margin is indicative of how much the gain should be decreased to make the system stable. |
| A. | 1 |
| B. | |
| C. | 1 |
| D. | 2 |
| Answer» B. | |
| 162. |
Examine the following statements A small size hydraulic actuator can develop good torque.It is easy to maintain a hydraulic system leak proof.Both linear and rotatary hydraulic actuators are available.Hydraulic power is more easily available than electric power. Which of the above statements are correct? |
| A. | all |
| B. | 1 and 2 only |
| C. | 1 and 3 only |
| D. | 2, 3 and 4 only |
| Answer» D. 2, 3 and 4 only | |
| 163. |
If there are |
| A. | two poles of G(s) in the left half plane |
| B. | two poles of G(s) in the right half plane |
| C. | three poles of G(s) in the right half plane |
| D. | four poles of G(s) in the right half plane |
| Answer» C. three poles of G(s) in the right half plane | |
| 164. |
Assertion (A): In an automobile the amount of fuel admitted to the engine is adjusted as per the difference between desired and actual speed.Reason (R): The control signal is the amount of fuel to be admitted to the engine. |
| A. | Both A and R are correct and R is correct explanation of A |
| B. | Both A and R are correct but R is not correct explanation of A |
| C. | A is correct but R is wrong |
| D. | R is correct but A is wrong |
| Answer» C. A is correct but R is wrong | |
| 165. |
In response to a unit step input the controller output in given figure is for |
| A. | proportional controller |
| B. | proportional plus integral controller |
| C. | integral controller |
| D. | none of the above |
| Answer» C. integral controller | |
| 166. |
For a stable system |
| A. | phase margin is positive but gain margin is negative |
| B. | gain margin is positive but phase margin is negative |
| C. | zero |
| D. | 90° |
| Answer» C. zero | |
| 167. |
For the unity feed back system of the given figure, the closed loop transfer function is |
| A. | |
| B. | |
| Answer» B. | |
| 168. |
Assertion (A): The function has a double pole at s = - 5.Reason (R): If the function [G(s)] (s + p)n for n = 1, 2, 3 ... has a finite non-zero value at s = - p, then s = - p is called a pole of order n. |
| A. | Both A and R are correct and R is correct explanation of A |
| B. | Both A and R are correct but R is not correct explanation of A |
| C. | A is correct but R is wrong |
| D. | R is correct but A is wrong |
| Answer» B. Both A and R are correct but R is not correct explanation of A | |
| 169. |
The radius and centre of M circles are given by |
| A. | |
| B. | |
| Answer» B. | |
| 170. |
The given figure shows dB magnitude plots for type 0, type 1 and type 2 systems. Out of these |
| A. | curves 1, 2, 3 are for type 0, 1, 2 systems respectively |
| B. | curves 1, 2, 3 are for type 2, 1, 0 systems respectively |
| C. | curves 1, 2, 3 are for type 1, 0, 2 systems respectively |
| D. | curves 1, 2, 3 are for type 1, 2, 0 systems respectively |
| Answer» B. curves 1, 2, 3 are for type 2, 1, 0 systems respectively | |
| 171. |
Assertion (A): When the phase margin of a control system is improved using a lead network, noise transmission increases.Reason (R): Phase lead compensation increases bandwidth. |
| A. | Both A and R are correct and R is correct explanation of A |
| B. | Both A and R are correct but R is not correct explanation of A |
| C. | A is correct but R is wrong |
| D. | R is correct but A is wrong |
| Answer» B. Both A and R are correct but R is not correct explanation of A | |
| 172. |
For the system shown in the given figure the time response to unit step input is |
| A. | |
| B. | c(t) = T(1 - e-t/T) |
| C. | c(t) = 1 - e-t/T |
| Answer» D. | |
| 173. |
Assertion (A): Integration in time domain is converted into division in s domainReason (R): |
| A. | A is correct but R is wrong |
| B. | R is correct but A is wrong |
| C. | the gain is increased beyond upper critical value |
| D. | the gain is decreased below lower critical value |
| Answer» C. the gain is increased beyond upper critical value | |
| 174. |
If G(s) H(s) = , the closed loop poles are on |
| A. | negative real axis |
| B. | jω axis |
| C. | right half plane |
| D. | either (a) or (b) |
| Answer» C. right half plane | |
| 175. |
For a second order system, the position of poles is shown in the given figure. This system is |
| A. | undamped |
| B. | overdamped |
| C. | underdamped |
| D. | critically damped |
| Answer» D. critically damped | |
| 176. |
In the given figure, P = Pm sin ωt. Then X(s) = |
| A. | |
| B. | |
| Answer» B. | |
| 177. |
Assertion (A): Industrial robots improve productivity.Reason (R): Robots can handle monotonous and complex jobs without error in operation. |
| A. | Both A and R are correct and R is correct explanation of A |
| B. | Both A and R are correct but R is not correct explanation of A |
| C. | A is correct but R is wrong |
| D. | R is correct but A is wrong |
| Answer» B. Both A and R are correct but R is not correct explanation of A | |
| 178. |
For G(jω) = |
| A. | magnitude is 1 at all frequencies and phase angle varies from 0 to - 180° as ω varies from 0 to ∞ |
| B. | magnitude is T at all frequencies and phase angle 0 |
| C. | magnitude is (1 + ω2T2)0.5 and phase angle varies from0 to 0 - 180° as ω varies from 0 to ∞ |
| D. | none of the above |
| Answer» B. magnitude is T at all frequencies and phase angle 0 | |
| 179. |
An RLC series circuit hasIf poles p1 and p1* are close to jω axis, then |
| A. | resonant frequency is high |
| B. | Q is high |
| C. | bandwidth is large |
| D. | Q is low |
| Answer» D. Q is low | |
| 180. |
Which of the following represents constant magnitude locus for M = 1? |
| A. | x = -0.5 |
| B. | x = 0 |
| C. | x2 + y2 = 1 |
| D. | (x + 1)2 + y2 = 1 |
| Answer» B. x = 0 | |
| 181. |
The block diagram of the given figure for |
| A. | On-off controller with integral gap |
| B. | Three position controller |
| C. | magnitudes of voltages applied to the two stator windings |
| D. | phase relation of voltages applied to the two stator windings |
| Answer» B. Three position controller | |
| 182. |
A feedback amplifier has forward gains A1, A2 and feedback factor β as shown in signal flow graph of the given figure. Because of feedback as shown in signal noise ratio at output will |
| A. | increase |
| B. | decrease |
| C. | be unaffected |
| D. | depend on value of β |
| Answer» D. depend on value of Œ≤ | |
| 183. |
Modelling error may occur due to |
| A. | neglecting the nonlinear characteristics of plant |
| B. | inaccuracy of parameters |
| C. | change of plant characteristics with time |
| D. | any of the above |
| Answer» E. | |
| 184. |
For the signal flow graph of the given figure consider the following statements It has three forward pathsIt has three individual loopsIt has two non touching loops Out of above the correct statements are |
| A. | 2, 3 |
| B. | 1, 3 |
| C. | a semi circle |
| D. | a circle |
| Answer» E. | |
| 185. |
For the system of the given figure, the undamped natural frequency of closed loop poles is |
| A. | 2 rad/sec |
| B. | 1 rad/sec |
| C. | 0.5 rad/sec |
| D. | 0.25 rad/sec |
| Answer» B. 1 rad/sec | |
| 186. |
I-PD controlled system has |
| A. | I, P and D actions in forward path |
| B. | I, P and D actions in feedback path |
| C. | I action in forward path but P and D action in feedback path |
| D. | I action in feedback path but P and D actioins in forward path |
| Answer» D. I action in feedback path but P and D actioins in forward path | |
| 187. |
In force current analogy, displacement x is analogous to |
| A. | charge |
| B. | magnetic flux linkage |
| C. | electrostatic energy |
| D. | voltage |
| Answer» C. electrostatic energy | |
| 188. |
If the Nyquist plot does not encircle the (-1 + j0) point the system is always stable. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 189. |
The system in the given figure has |
| A. | good gain and phase margins |
| B. | good gain margin and poor phase margin |
| C. | poor gain and phase margins |
| D. | poor gain margin but good phase margin |
| Answer» C. poor gain and phase margins | |
| 190. |
Nyquist stability criterion uses open loop frequency response characteristics. |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» B. 2 | |
| 191. |
Which dc servomotor requires strongest permanent magnet? |
| A. | Surface wound with stationary rotor |
| B. | Either (a) or (b) |
| C. | constant magnitude loci |
| D. | constant phase angle loci |
| Answer» D. constant phase angle loci | |
| 192. |
Which of the following is not correct for two phase servomotor? |
| A. | Rotor resistance is low |
| B. | Torque speed curve is linear |
| C. | 1/101 |
| D. | 1/100 |
| Answer» D. 1/100 | |
| 193. |
Consider the following statements: If any root of characteristic equation has a positive real part the impulse response is unbounded and system is unstable.If all the roots of a characteristic equation have negative real parts, the impulse response decays to zero.If one or more non-repeated roots of characteristic equation are on jω axis impulse response is bounded but the system is unstable. Which of the above equations are correct? |
| A. | 1, 2 and 3 |
| B. | 1 and 2 only |
| C. | 1 and 3 only |
| D. | 2 and 3 only |
| Answer» B. 1 and 2 only | |
| 194. |
Given figure shows a unity feedback system. The ratio of time constants for open loop and closed loop response are |
| A. | 0.042361111111111 |
| B. | 0.084027777777778 |
| C. | 0.12638888888889 |
| D. | 0.085416666666667 |
| Answer» E. | |
| 195. |
The log magnitude for the system in the given figure is (where T = RC) |
| A. | 20 log (1 + ωT) |
| B. | -20 log (1 + ωT) |
| C. | -10 log (1 + ω2T2) |
| D. | -20 log (1 + ω2T2) |
| Answer» D. -20 log (1 + œâ2T2) | |
| 196. |
The transfer function can be for |
| A. | lead compensator |
| B. | lag compensator |
| C. | either (a) or (b) |
| D. | neither (a) nor (b) |
| Answer» B. lag compensator | |
| 197. |
A first order element yields almost exact duplication only for constant or slowly varying phenomenon. |
| A. | 1 |
| B. | |
| C. | both phase and gain margin are negative |
| D. | both phase and gain margin are positive |
| Answer» B. | |
| 198. |
The relative stability of a system is given by |
| A. | gain margin alone |
| B. | phase margin alone |
| C. | both phase and gain margins |
| D. | either (a) or (b) |
| Answer» D. either (a) or (b) | |
| 199. |
For the system in the given figure, the characteristic equation is |
| A. | s2 + s(3 + 6a) + 6 = 0 |
| B. | s2 + s(3 + 12a) + 12 = 0 |
| C. | s2 + 3s = 0 |
| D. | s2 + 6s = 0 |
| Answer» B. s2 + s(3 + 12a) + 12 = 0 | |
| 200. |
Assertion (A): When the forward gain of a system is increased, the transient response becomes oscillatory.Reason (R): Increasing the forward gain reduces steady state error. |
| A. | Both A and R are correct and R is correct explanation of A |
| B. | Both A and R are correct but R is not correct explanation of A |
| C. | A is correct but R is wrong |
| D. | R is correct but A is wrong |
| Answer» B. Both A and R are correct but R is not correct explanation of A | |