1) Thermistors which have a very high temperature co-efficient of resistivity belong to the class of solid called________________? a. Dielectrics b. Insulators c. Semi conductors d. Conductors
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2) What is the Laplace transform of sin t ? a. 1/(s2 + 1) b. s/(1 + s2) c. 1/(s2 – 1) d. s/(s2 – 1)
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3) Silver point temperature is ______________ °C? a. 760.5 b. 860.5 c. 960.5 d. 1060.5
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4) A first order system with unity gain and time constant η is subjected to a sinusoidal input of frequency w = 1/η. The amplitude ratio for this system is______________? a. 0 b. 0.5 c. 1/√2 d. 0.25
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5) Water is flowing through a series of four tanks and getting heated as shown in figure. It is desired to design a cascade control scheme for controlling the temperature of water leaving the tank 4 as there is a disturbance in the temperature of a second stream entering the tank 2. Select the best place to take the secondary measurement for the second loop? a. Tank 1 b. Tank 2 c. Tank 3 d. Tank 4
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6) Which of the following is not suitable for measuring the temperature of a red hot object in the range of 800 – 1600°C ? a. Optical pyrometer b. Radiation pyrometer c. Photoelectric pyrometer d. Thermocouples
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7) Pyrometry refers to the measurement of temperature_________________? a. With the mercurial thermometer upto 350°C b. Directly c. Which is of higher magnitude d. All A., B. & C.
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8) Ordinary mercury in glass thermometer is used for measuring temperature upto 120°C. However, for measuring higher temperature upto __________ °C, thermometer is made by filling nitrogen under pressure above the mercury, which stops the evaporation of mercury and reduces the chance of broken thread of mercury? a. 250 b. 350 c. 550 d. 700
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9) According to Bode stability criterion, a system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at frequency for which phase lag is_________________? a. 0° b. 45° c. 90° d. 180°
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10) Mcleod gauge measures the _____________ pressure? a. Positive b. Sub-atmospheric c. Very high d. Atmospheric
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11) Continuous measurement of moisture content of paper in paper industry is done by measuring the_________________? a. Thermal conductivity through the paper b. Electrical resistance through the paper c. Magnetic susceptibility d. None of these
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12) Liquid column manometers are used for measuring the pressure ______________ kgf/cm2? a. > 2 (gage) b. < 3 (gage) c. < 10 (gage) d. < atmospheric
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13) Which is the strongest paramagnetic gas ? a. CO2 b. O2 c. NO d. NO2
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14) Maximum differential pressure in liquid manometer is ______________ psi? a. 20 b. 30 c. 40 d. 50
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15) Which of the following instruments is not used for measuring sub-zero (<0°) temperatures ? a. Platinum resistance thermometer b. Mercury in glass thermometer c. Vapor pressure thermometer d. Radiation pyrometer
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16) Which of the following cannot measure a temperature of 1600°C ? a. Platinum resistance thermometer b. Thermocouple c. Photo-electric pyrometer d. Radiation pyrometer
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17) In a second order under damped system, the_________________? a. Time required for the response of first reach its ultimate value is called the response time b. Overshoot (which is a measure of how much the response exceeds the ultimate value) increase with the decrease of damping co-efficient c. Decay ratio (which is the ratio of the sizes of successive peaks) is equal to the reciprocal of overshoot d. None of these
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18) “A control system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at the crossover frequency.” This is _______________ criterion? a. Bode stability b. Nyquist c. Routh stability d. None of these
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19) A typical example of a physical system with under damped characteristic is a____________________? a. U-tube manometer b. Spring loaded diaphragm valve c. CSTR with first order reaction d. Thermocouple kept immersed in a liquid filled thermowell
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20) In a closed loop system, the process to be controlled is an integrating process with transfer function 1/2s. The controller proposed to be used in an integral controller with transfer function 1/T1s. When a step change in set point is applied to such a closed loop system, the controlled variable will exhibit__________________? a. Overdamped response b. Underdamped response c. Undamped response d. Unstable response
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