MCQOPTIONS
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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.
| 451. |
Consider the following statements regarding negative feedback It increases system gainIt improves sensitivityIt improves system stability Which of these are not correct? |
| A. | all |
| B. | 1, 2 |
| C. | 1, 3 |
| D. | 1 only |
| Answer» E. | |
| 452. |
A system has its two poles on the negative real axis and one pair of poles lies on jω axis. The system is |
| A. | stable |
| B. | unstable |
| C. | limitedly stable |
| D. | either (a) or (c) |
| Answer» D. either (a) or (c) | |
| 453. |
For type 1 system the velocity lag error is |
| A. | inversely proportional to bandwidth of system |
| B. | directly proportional to gain constant |
| C. | inversely proportional to gain constant |
| D. | independent of gain constant |
| Answer» D. independent of gain constant | |
| 454. |
If the Nyquist plot encircles the (-1 + j0) point clockwise once or more number of times, the system is unstable. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 455. |
In position control system the device used for providing rate feedback voltage is |
| A. | potentiometer |
| B. | synchro-transmitter |
| C. | synchro-transformer |
| D. | tacho generator |
| Answer» E. | |
| 456. |
PID controlled system has |
| A. | P and I actions in forward path and D action in feedback path |
| B. | P and I actions in feedback path and actions in forward path |
| C. | All the three (i.e., P, I and D) actions in forward path |
| D. | All the three (i.e., P, I and D) actions in feedback path |
| Answer» B. P and I actions in feedback path and actions in forward path | |
| 457. |
Assertion (A): Feedback control systems offer more accurate control than open loop systems.Reason (R): The feedback path establishes a link for comparison of input and output and subsequent error correction. |
| 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 | |
| 458. |
The effect of adding poles and zeros can be determined quickly by |
| A. | Nichols chart |
| B. | Nyquist plot |
| C. | Bode plot |
| D. | Root locus |
| Answer» D. Root locus | |
| 459. |
If then f(t) = |
| A. | cos θ0t |
| B. | sin ω0t |
| C. | eat cos ω0t |
| D. | e-at cos ω0t |
| Answer» E. | |
| 460. |
Nyquist stability criterion is based on a theorem from the theory of complex variables. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 461. |
If C is thermal capacitance, m is mass of liquid and c is specific heat, then |
| A. | C = mc |
| B. | c = mC |
| C. | m = cC |
| D. | C = (mc)2 |
| Answer» B. c = mC | |
| 462. |
For overdamped systems a quadratic factor in transfer function can be replaced by two first order factors with real poles |
| A. | 1 |
| B. | |
| Answer» B. | |
| 463. |
Assertion (A): An on off controller gives rise to oscillation of the output between two limits.Reason (R): Location of a pair of poles on jω axis gives rise to self sustained oscillations in the output. |
| 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 | |
| 464. |
Stepper motors find applications in |
| A. | X-Y plotters |
| B. | numerically controlled machining equipment |
| C. | printers |
| D. | all of the above |
| Answer» E. | |
| 465. |
The angular location of poles depends on |
| A. | undamped natural frequency |
| B. | damping ratio |
| C. | both (a) and (b) |
| D. | neither (a) nor (b) |
| Answer» C. both (a) and (b) | |
| 466. |
Optical encoders most commonly used in control systems are |
| A. | absolute encoders |
| B. | secondary encoders |
| C. | incremental encoders |
| D. | none of the above |
| Answer» D. none of the above | |
| 467. |
Assertion (A): The concept of impulse function is useful in differentiating discontinuous functions.Reason (R): |
| 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 | |
| 468. |
The system in the given figure |
| A. | will be unstable due to the presence of positive feedback in the inner loop |
| B. | may be stabilized by the negative feedback outer loop |
| C. | can never be stable |
| D. | will always be stable |
| Answer» C. can never be stable | |
| 469. |
At low frequencies the factor e-jωT and behave simple. |
| A. | 1 |
| B. | |
| C. | 1, 2, 3 |
| D. | 1, 2 |
| Answer» B. | |
| 470. |
While forming Routh's array, the situation of a row of zeros indicates that the system |
| A. | has symmetrically located roots |
| B. | is not sensitive to variations in gain |
| C. | is stable |
| D. | is unstable |
| Answer» B. is not sensitive to variations in gain | |
| 471. |
The transfer function can be for |
| A. | lead compensator |
| B. | lag compensator |
| C. | lead-lag compensator |
| D. | either (a) or (b) |
| Answer» D. either (a) or (b) | |
| 472. |
DC tachogenerator can be used in |
| A. | speed control system |
| B. | position control system |
| C. | both (a) and (b) |
| D. | neither (a) nor (b) |
| Answer» D. neither (a) nor (b) | |
| 473. |
For a second order system ωn is natural frequency, ωd is frequency of damped oscillations and ζ is damping factor. Then |
| A. | ωd = ωn ξ |
| B. | ωd = ωn (1 - ξ)2 |
| C. | ωd = ωn (1 - ξ)0.5 |
| D. | ωd = ωn (1 - ξ2)0.5 |
| Answer» E. | |
| 474. |
In a two phase servomotor, if R is rotor resistance, X is rotor reactance, L is rotor length D is rotor diameter then |
| A. | and are both small |
| B. | is large but is small |
| C. | is small but is large |
| D. | and are both large |
| Answer» D. and are both large | |
| 475. |
Assertion (A): When performance specifications are given in term of transient response characteristics, root locus method is a suitable method.Reason (R): When performance specifications in terms of state variables are given, modern control methods can be used. |
| 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 | |
| 476. |
If damping ratio is 0.5, the lines joining complex poles with origin are inclined to negative real axis at |
| A. | ± 90° |
| B. | ± 60° |
| C. | ± 45° |
| D. | ± 30° |
| Answer» C. ¬± 45¬∞ | |
| 477. |
Which of the following rotors are used in two phase ac servomotor? Solid iron rotorSquirrel cage rotorDrag cup rotor Of the above the correct ones are |
| A. | 1, 2, 3 |
| B. | 1, 2 |
| C. | 2, 3 |
| D. | 1, 3 |
| Answer» D. 1, 3 | |
| 478. |
Assertion (A): Potentiometers can not be used as error detectors in position control systems.Reason (R): The resolution of a potentiometer places an upper limit on its accuracy |
| 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» E. | |
| 479. |
In a synchro transmitter |
| A. | input is angular position of rotor shaft and output is stator voltages |
| B. | input is stator voltages and output is angular position of shaft input is rotor voltage and output is angular position of rotor shaft |
| C. | input is rotor voltage and output is angular position of rotor shaft |
| D. | input is angular position of rotor shaft and output is rotor voltage |
| Answer» B. input is stator voltages and output is angular position of shaft input is rotor voltage and output is angular position of rotor shaft | |
| 480. |
In a minimum phase system |
| A. | all poles lie in the left half plane |
| B. | all zeros lie in the left half plane |
| C. | all poles lie in the right half plane |
| D. | all except one pole or zero lie in the left half plane |
| Answer» C. all poles lie in the right half plane | |
| 481. |
The entries in the first column of Routh array of a fourth order are 5, 2, - 0.1, 2, 1. The number of poles in the right half plane are |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» C. 3 | |
| 482. |
For the function G(s) = the poles are at |
| A. | s = 0 and s = ‚àû |
| B. | s = j2np where n = 0, 1, 2 |
| C. | s = ± j2np where n = 0, 1, 2.. |
| D. | none of the above. |
| Answer» D. none of the above. | |
| 483. |
Integral control action |
| A. | removes offset |
| B. | may lead to oscillatory response |
| C. | both (a) and (b) |
| D. | neither (a) nor (b) |
| Answer» D. neither (a) nor (b) | |
| 484. |
Which control action can never be used alone? |
| A. | Proportional |
| B. | Derivative |
| C. | Integral |
| D. | Both (b) and (c) |
| Answer» C. Integral | |
| 485. |
The magnitude of transport lag factor is always zero. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 486. |
A lag compensator is essentially a |
| A. | low pass filter |
| B. | high pass filter |
| C. | band pass filter |
| D. | either (a) or (b) |
| Answer» B. high pass filter | |
| 487. |
In the given figure the input is x(t) = A sin ωt. The steady state output y(t) = |
| A. | A sin (ωt + φ) where φ = tan-1 |G(jω)| |
| B. | |G(jω)| A sin [ωt + ∠G(jω)] |
| C. | |G(jω)| A sin [2ωt + ∠G(jω)] |
| D. | A G(jω) sin [ωt + ∠G(jω)] |
| Answer» C. |G(jœâ)| A sin [2œât + ‚à†G(jœâ)] | |
| 488. |
The signal flow graph of a system is shown in the given figure. The effect of disturbance TD can be reduced by |
| A. | increasing G2 (s) |
| B. | decreasing G2 (s) |
| C. | increasing G1 (s) |
| D. | decreasing G1 (s) |
| Answer» D. decreasing G1 (s) | |
| 489. |
A compensator has its pole and zero as shown in the given figure |
| A. | lag compensator |
| B. | lead compensator |
| C. | lead-lag compensator |
| D. | series compensator |
| Answer» C. lead-lag compensator | |
| 490. |
Assertion (A): Integral control action is sometimes called reset control.Reason (R): Reset rate is expressed as number of repeats per unit time. |
| 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 | |
| 491. |
The constant magnitude of G(s) plane are |
| A. | a family of straight horizontal lines |
| B. | a family of straight inclined lines with positive slope |
| C. | a family of straight inclined lines with negative slope |
| D. | a family of circles |
| Answer» E. | |
| 492. |
For very low frequencies, v0/vi in the given figure equals |
| A. | 1 |
| B. | 0 |
| C. | ‚àû |
| D. | 0.5 |
| Answer» B. 0 | |
| 493. |
The open loop frequency response of a unity feed back system is as underThe gain margin and phase margin respectively are |
| A. | 20 dB and 15° |
| B. | 20 dB and 25° |
| C. | 6 dB and 15° |
| D. | 6 dB and 25° |
| Answer» D. 6 dB and 25¬∞ | |
| 494. |
In an integral controller |
| A. | the output is proportional to input |
| B. | the rate of change of output is proportional to input |
| C. | the output is proportional to rate of change of input |
| D. | none of the above |
| Answer» C. the output is proportional to rate of change of input | |
| 495. |
If the characteristic equation is (λ + 1) (λ + 2) (λ + 3) = 0, the eigen values are |
| A. | -1, -2, -3 |
| B. | 1, 2, 3 |
| C. | 0, 1, 2 |
| D. | 0, 2, 3 |
| Answer» B. 1, 2, 3 | |
| 496. |
A system has transfer function. If a sinusoidal input of frequency ω is applied the steady state output is of the form |
| A. | |
| B. | K1 K2 (1 + jω/T) |
| Answer» B. K1 K2 (1 + jœâ/T) | |
| 497. |
Assertion (A): When the performance of a stable second order system is improved by a PID controller, the system may become unstable.Reason (R): PID controller increases the order of the system to 3. |
| 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 | |
| 498. |
The gain margin for a stable system |
| A. | has a positive decibel value |
| B. | has a negative decibel value |
| C. | has a large negative decibel value |
| D. | none of the above |
| Answer» B. has a negative decibel value | |
| 499. |
The ac motor used in servo applications is |
| A. | single phase induction motor |
| B. | two phase induction motor |
| C. | 3 phase induction motor |
| D. | synchronous motor |
| Answer» C. 3 phase induction motor | |
| 500. |
The given figure shows three Nyquist plots of G(s) H(s) = e-sT/[s(s + 1)] for different values of T. The curves 1, 2, 3 can be |
| A. | for T = 0, 0.5 and 1 respectively |
| B. | for T = 1, 0.5 and 0 respectively |
| C. | for T = 0.5, 1 and 0 respectively |
| D. | for T = 0, 1 and 0.5 respectively |
| Answer» B. for T = 1, 0.5 and 0 respectively | |