objective questions on instrumentation and control engineering

objective questions on instrumentation and control engineering
Instrumentation and control Engineering Solved MCQ
Instrumentation and Control Systems Sample Questions

1. Which one of the following detectors is used in bridge measurements of 50 Hz?
(a) Vibration galvanometer
(b) Ballistic galvanometer
(c) D’Arsonval galvanometer
(d) Trivector meter

Ans:-A


2. When a first order instrument with a time constant of 10 m sec is used to measure an input x = 10 sin 100 t, the time lag will be
(a) tan -1 1 / 100 seconds
(b) 100 tan -1 1 seconds
(c) 100 / tan-1 1seconds
(d) tan -1 1 seconds

Ans:-A

3. Which of the following can be considered to be the advantages of Maxwell’s inductance-capacitance bridge when compared to other types of bridges?
1. Balance equation of real part is independent of that of imaginary part.
2. Frequency term does not figure in the equation.
3. When balance is achieved, the value of capacitance multiplied by resistances gives the value of inductance.
4. The bridges is capable of measuring ‘Q’ of coils of a very wide range, that is, from 1 to 200.
Select the correct answer using the codes given below:
Codes:
(a) 1,2and3
(b) 1,3and4
(c) 1,2and4
(d) 2,3and4

Ans:-A

4. A voltmeter has a uniform scale with 100 divisions. The full-scale reading is 10 V and could be read upto 1/10 of a scale division with some degree of certainty. It’s resolution is
(a) 0.1 V
(b) 0.02 V
(c) 0.01 V
(a) 0.00 1 V

Ans:-C

5. A piezoelectric transducer has an output voltage of 3 V at no-load conditions. It has a capacitance of 250 pF. If it is connected to a load capacitance of 125 pF, the voltage across the load at high frequencies will be
(a) 3V
(b) 2V
(c) 1V
(d) not determinable from the given data

Ans:-C


Directions: The following items consist of two statements, one labelled the ‘Assertion A’ and the other labelled the ‘Reason R’. You are to examine these two statements carefully and decide f the Assertion A and the Reason R are individually true and f so, whether the Reason is a correct explanation of the Assertion. Select your answer to these items using the codes given below and mark your answer sheet accordingly.
Codes:
(a) Both A and R is true and R is the correct explanation of A
(b) Both A and R is true but R is not a correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true



6. Assertion (A): An integrator is preferred to a differentiator in an analog computer.
Reason (R): Integrator is faster than differentiator.

Ans:-A


7. Assertion (A): Commercial PCM generally use a 6-bit code.
Reason (R): This is a compromise between quantisation noise and channel bandwidth requirements.

Ans:-B

8. Which of the following factor(s) is/are associated with the determination of step response of a time invariant linear network?
1. Initial conditions of the network
2. Time of application of the input
3. Size of the step input
Select the correct answer using the codes given below:
Codes:
(a) l, 2 and 3
(b) l and 3
(c) 2 and 3
(d) 3 alone

Ans:-B

9. The presence of negative feedback in a control system
(a) Increases accuracy and reduces bandwidth
(b) Reduces bandwidth and increases distortion
(c) Increases the effect of nonlinearities and reduces distortion
(d) Reduces distortion and increases bandwidth

Ans:-D

10. A system with a proportional controller shows steady-state error to a step input. It can be reduced by
(a) Rate feedback
(b) Increasing the controller gain
(c) Adding integral action to the controller
(d) Positive feedback

Ans:-B

11. Consider the following transfer function of a phase-lead network:
1+0.2s / 1 + 0.05s
The angular frequency for maximum phase shift of the above network is
(a) 40
(b) 30
(c) 20
(d) l0

Ans:-A


12. A control system is represented as
X = AX + BU
Y = CX
Consider the following statements in this regard:
1. The pair (AB) is controllable implies that the pair (ATBT) is observable.
2. The condition of controllability depends on the matrices A and B of the system.
3. The pair (AC) is observable implies that the pair (ATCT) is controllable.
Of these statements:
(a) 1, 2 and 3 are correct
(b) 1 and 2 are correct
(c) 2 and 3 are correct -
(d) 1 and 3 are correct

Ans:-A


13. The state representation for a second-order system is given by
x l = —x l + u
x2 = x1— 2x2 + u
Consider the following statements regarding the above systems:
1. The system is completely state-controllable.
2. If x1, is the output, then the system is output controllable.
3. If x2 is the output, then the system is output controllable.
Of these statements:
(a) 1, 2 and 3 are correct
(b) 1 and 2 are correct
(c) 2 and 3 are correct
(d) 1 and 3 are correct

Ans:-C

14. In a properly biased transistor with beta = 50, the voltage across the collector resistance of value 2 K is 2 V. The base current in CE and CB configurations would be respectively
(a) 0.02 mA, 0.02 mA
(b) 0.01 mA, 0.02 mA
(c) 0.05 mA, 0.01 mA
(d) 0.01 mA, 0.01 mA

Ans:-A


15. For a common-emitter transistor circuit, the cut- in voltage is taken as the one at which the collector current has reached ‘X’ of the maximum saturation current. The value of X is
(a) 0.5%
(b) 1%
(c) 5%
(d) 10%

Ans:-D





16. A Hi- Fi amplifier consists of the following stages:
1. Audio amplifier
2. Power amplifier
3. Driver
4. Pre-driver
5. Pre-amplifier
The correct sequence in which these stages appear from the input end to the output end in the amplifier, is
(a) 5, 2,4,3,1
(b) 2, 4,3,5,1
(c) 4, 3,5,1,2
(d) 5, 1,4,3,2

Ans:-C

17. The Bootstrap and Miller Integrator type time base generators, in the ideal case, are characterized by ampler gains of
(a) —and + 1 respectively
(b) + 1 and —? respectively
(c) +1
(d)-?

Ans:-B






18.. Consider the following applications:
1. Signal adder
2. Signal multiplier
3. AM demodulator
4. Frequency multiplier
5. Pulse modulator
A balanced modulator is useful as
(a) 1, 2,4and 5
(b) 1, 3, and 5
(c) 2, 3, 4and 5
(d) 2, 3 and 4

Ans:-A

19. Which of the following can be considered to be the advantages of FET amplifiers as compared to BJT amplifiers?
1. Higher input impedance
2. Good bias stability
3. Higher gain-bandwidth product
4. Lower noise figure.
Select the correct answer using the codes given below:
Codes:
(a) l, 2and3
(b) 1,2and4
(c) 2, 3 and 4
(d) 1, 3 and 4

Ans:-B

20. Which of the following can be considered to be the advantages of hybrid ICs over monolithic ICs?
1. Greater design flexibility
2. Lower cost
3. Improved performance, hybrid ICs can combine the best performance features of all ICs : MOS, bipolar, thin film and thick
4. Heat removal from hybrid circuit is easier
Select the correct answer using the codes given below:
Codes:
(a) 1,2and3
(b) l, 3and4
(c) 1,2and4
(d) 2,3and4

Ans:-C