Important Paper GATE  Instrumentation Engineering

1. A signal m(t) varies from -3.5 V to +3.5 V with an average power of 3W. The signal is quantized using a midtread type quantizer and subsequently binary encoded. With the codeword of length 3, the signal to quantization noise ratio in dB is_______.
(a) 15.55                                       
(b) 15.54
(c) 15.52                                       
(d) 15.56
Ans. (d)
2. A 200 mV full scale dual-slope 3½ digit DMM has a reference voltage of 100 mV and a first integration time of 100 ms. For an input of [100 + 10 Cos(100𝜋t)] mV, the conversion time (without taking the auto-zero phase time into consideration in millisecond is ______.
(a) 100                                          
(b) 300
(c) 150                                          
(d) 200
Ans. (d)
3. A coil is tested with a series type Q-meter. Resonance at a particular frequency is obtained with a capacitance of 110pF. When the frequency is doubled, the capacitance required for resonance is 20pF. The distributed capacitance of the coil in picofarad is ______.
(a) 10                                            
(b)11
(c) 9                                               
(d) 8
Ans. (a)
4. A symmetrical three-phase three-wire RYB system is connected to be balanced delta-connected load. The RMS values of the line current and line-to-line voltage are 10 A and 400 V respectively. The power in the system is measured using the two wattmeter method. The first wattmeter connected between R-line and Y-line reads zero. The reading of the second wattmeter (connected between B-line and Y-line) in watt is ________.
(a) -3364.10                                 
(b) -3464.10
(c) -3264.10                                 
(d) -3554.10
Ans. (b)
5. A 31/2 digit DMM has an accuracy specification of + 1%  of full scale (accuracy class 1). A reading of 100.0 mA is obtained on its 200 mA full scale range. The worst case error in the reading in milliampere is  ______.
(a) 2.0; 2.0                                   
(b) 2.0; 2.1
(c) 2.1; 2.0                                    
(d) 2.1; 2.1
Ans. (d)
6. A peizo-electric type pressure sensor has a sensitivity of 1 mV/kPa and a band width of 300 Hz to 300 kHz. For a constant (dc) pressure of 100 kPa, the steady state output of the sensor in milivolt is _______.
(a) 1                                               
(b) 0
(c) 2                                               
(d) 4
Ans. (b)
7. The overwhelming number of people infected with rabies in India has been flagged by the World Health Organization as a source of concern. It is estimated that inoculating 70% of pets and stray dogs against rabies can lead to a significant reduction in the number of people infected with rabies. Which of the following can be logically inferred from the above sentences?
(a) The number of people in India infected with rabies in high.
(b) The number of people in other parts of the world who are infected with rabies is low.
(c) Rabies can be eradicated in India by vaccinating 70% of stray dogs.
(d) Stray dogs are the main source of rabies worldwide.
Ans. (a)
8. A flat is shared by four first year undergraduate students. They agreed to allow the oldest of them to enjoy some extra space in the flat. Manu is two month older than Sravan, who is three month younger than Trideep. Pavan is one month older than Sravan. Who should occupy the extra space in the flat?
(a) Manu                                      
(b) Sravan
(c) Trideep                                    
(d) Pavan
Ans. (c)
9. Find the area bounded by the lines 3𝑥 + 2𝑦 = 14, 2𝑥 - 3𝑦 = 5 in the first quadrant.
(a) 14.95                                       
(b) 15.25
(c) 15.70                                       
(d) 20.35
Ans. (b)
10. A straight line is fit to a data set (ln x,y). This line intercepts the abscissa at ln x=0.1 and has a slope of -0.02. What is the value of y at x=5 from the fit?
(a) -0.030                                     
(b) -0.014
(c) 0.014                                       
(d) 0.030
Ans. (a)
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