Process Control and Instrumentation MCQs : This section focuses on the "Process Control and Instrumentation". These Multiple Choice Questions (MCQs) should be practiced to improve the Process Control and Instrumentation skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.
Question 1
A system with a double pole at the origin is unstable since the corresponding term in the time domain
A. Is a constant
B. Grows exponentially with time
C. Grows linearly with time
D. Decays linearly with time
Question 2
Which of the following thermocouples has the widest temperature measurement range?
A. Iron-constantan
B. Chromel-alumel
C. Copper-constantan
D. Platinum-platinum/rhodium
Question 3
Characteristic equation is the denominator of __________ loop transfer function.
A. Open
B. Closed
C. Both A & B
D. Neither A nor B
Question 4
Routh stability method uses __________ loop transfer function.
A. Open
B. Closed
C. Either A or B
D. Neither A nor B
Question 5
To increase the speed of response of a pressure spring liquid or gas expansion thermometer, the clearance space between the thermometer bulb and the thermal well should not be filled with
A. Air
B. A metal powder or graphite
C. Oil
D. Mercury
Question 6
Which of the following can not measure a temperature of 1600°C ?
A. Platinum resistance thermometer
B. Thermocouple
C. Photo-electric pyrometer
D. Radiation pyrometer
Question 7
Very low pressure is expressed in microns(μ), which is equal to __________ mm of Hg coloumn (absolute) at 0°C.
A. 0.0001
B. 0.001
C. 0.01
D. 0.1
Question 8
Which thermocouple can be used to measure a temperature of around 1400°C ?
A. Copper-constantan
B. Aluminium-chromel
C. Platinum-platinum+rhodium
D. None of these
Question 9
Mercury thermometer can be used to measure the temperature upto __________ °C.
A. 100
B. 250
C. 350
D. 750
Question 10
Smoke density of the flue gas going out of the chimney is measured by a
A. polarograph
B. thermal conductivity meter
C. photo electric cell
D. chromatograph
Question 11
A pyranometer is an instrument used for measuring the
A. Beam radiation
B. Global radiation
C. Bright sunshine period
D. None of these
Question 12
Temperature of __________ can not be measured by an optical or radiation pyrometer.
A. Hot blast (air) from stoves
B. Molten slag flowing out of blast furnace
C. Combustion space in boilers
D. Rotary limestone calcination kiln
Question 13
Thermistors are used in __________ devices.
A. Voltage measuring
B. Temperature measuring
C. Temperature compensating
D. Both B & C
Question 14
Temperature of molten pig iron (1450°C) and molten slag (1500°C) flowing out of a blast furnace is measured by a/an
A. Chromel-alumel thermocouple
B. Optical pyrometer
C. Radiation pyrometer
D. Either B or C
Question 15
For a feed back control system to be stable, the
A. Roots of the characteristic equation should be real
B. Poles of the closed loop transfer function should lie in the left half of the complex plane
C. Bode plots of the corresponding open loop transfer function should monotoni-cally decrease
D. Poles of the closed loop transfer function should lie in the right half of the complex plane
Question 16
Thermistor, which has high temperature co-efficient of resistivity, is used as the sensing element in resistance thermometer. It is a/an
A. insulator
B. conductor
C. solid semi-conductor
D. liquid semi-conductor
Question 17
Typical specifications for design stipulates the gain margin and phase margin to be respectively
A. > 1.7 and > 30°
B. < 1.7 and > 30°
C. < 1.7 and < 30°
D. > 1.7 and < 30°
Question 18
Select the correct statement from the following.
A. The frequency response of a pure capacity process is unbounded.
B. The phase lag of a pure time delay system decreases with increasing frequency.
C. The amplitude ratio of a pure capacity process is inversely proportional to frequency.
D. The amplitude ratio of a pure time delay system increases with frequency.
Question 19
Working principle of mercury in glass thermometer is
A. Volumetric expansion
B. Pressure rise with temperature
C. Linear expansion
D. None of these
Question 20
Maximum differential pressure in liquid manometer is __________ psi.
A. 20
B. 30
C. 40
D. 50
Question 21
Compositional analysis of flue gas coming out of a furnace in respect of O₂ and CO₂% can be continuously done by a/an
A. Orsat apparatus
B. Thermal conductivity cell
C. Zirconia probe
D. Chromatograph
Question 22
Meleoid gauge measures the __________ pressure.
A. Positive
B. Sub-atmospheric
C. Very high
D. Atmospheric
Question 23
What is the Laplace transform of impulse input having magnitude 'X' ?
A. X
B. X²
C. 1/X
D. 1
Question 24
Magnetic flowmeters are generally not used for the velocity/flow measurement of hydrocarbons due to their
A. Low thermal conductivity
B. Low electrical conductivity
C. High viscosity index
D. Low flash point
Question 25
Flow rate of those fluids which are insensitive to changes in their density, viscosity or flow velocity profile can be best measured by a
A. Magnetic flowmeter
B. Pitot tube
C. Flow nozzle type flowmeter
D. Turbine flowmeter
Question 26
Composition of natural gas is determined by the
A. Haldane apparatus
B. Mass spectrometer
C. Chromatograph
D. Both B and C
Question 27
Configuration of Bourdon spring tube is never made of __________ shape.
A. Circular
B. Semi-circular
C. Helical
D. Spiral
Question 28
Response of a system to a sinusoidal input is called __________ response.
A. impluse
B. unit step
C. frequency
D. none of these
Question 29
Temperature measurement by optical pyrometer is done above __________ point, which is 1063°C.
A. Antimony
B. Gold
C. Silver
D. Nickel
Question 30
Which of the following controllers has maximum offset?
A. P-controller
B. P-I controller
C. P-D controller
D. P-I-D controller
Question 31
Working principle of bimetallic thermometers is difference in linear co-efficient of thermal expansion of two strips of different metals welded together. Which of the following has the maximum thermal co-efficient of linear expansion?
A. Nickel
B. Brass
C. Chromel
D. Invar
Question 32
Flow rate measurement of hostile acids and alkalis can be most suitably done by a/an
A. Venturimeter
B. Orificemeter
C. Magnetic flow meter
D. Hot wire anemometer
Question 33
Positioning controllers are used for
A. Low loads
B. Temperature changes
C. High loads
D. Flow rate changes
Question 34
Emf developed by a thermocouple while measuring a temperature of 400°C is 22 mV. The type of thermocouple used is
A. Chromel-alumel
B. Iron-constantan
C. Platinum-rhodium
D. Platinum-platinum+rhyodium
Question 35
The level of a liquid under pressure can be determined using
A. Bubbler system
B. Differential pressure manometer
C. Diaphragm box system
D. Air-trap system
Question 36
Working principle of disappearing filament type optical pyrometer is based on the
A. Wien's law
B. Seebeck effect
C. Kirchoff's law
D. Peltier effect
Question 37
The temperature of tempering oil baths maintained at 400°C during heat treatment of steel is measured by a/an __________ thermocouple.
A. chromel-alumel
B. iron-constantan
C. platinum-platinum/rhodium
D. none of these.
Question 38
Pick out the first order system from among the following.
A. Damped vibrator.
B. Mercury in glass thermometer kept in boiling water.
C. Interacting system of two tanks in series.
D. Non-interacting system of two tanks in series.
Question 39
Operating range of a temperature measuring instrument is 800 to 1600°C. It could be a/an __________ pyrometer.
A. Radiation
B. Optical
C. Photoelectric
D. None of these
Question 40
Which of the following thermocouples will give the highest output for the same value of hot and cold junction temperature ?
A. Platinum-platinum + rhodium.
B. Iron-constantan.
C. Chromel-constantan.
D. All will give the same output.
Question 41
Nitrogen gas constant volume thermometer is suitable for measuring a temperature of __________ °C.
A. 0-100
B. < 0
C. > 100
D. > 50
Question 42
__________ is an example of distributed parameter system
A. Tubular reactor
B. CSTR
C. On-off controller
D. None of these
Question 43
Polarograph is meant for the analysis of
A. Gaseous mixture
B. Miscible liquids
C. Solids
D. Isotopes
Question 44
Which of the following filled system expansion thermometer has the capability to measure the lowest temperature?
A. Mercury in glass thermometer
B. Mercury in steel thermometer
C. Alcohol in glass thermometer
D. Fused metal (Na or K) in steel thermometer
Question 45
Psychrometer determines the
A. Humidity of gases
B. Moisture content of solids
C. Water of crystallisation
D. Hygroscopic nature of solids
Question 46
Which of the following is not a differential pressure flow meter?
A. Rotameter
B. Flow nozzle
C. Orificemeter
D. Venturimeter
Question 47
Zirconia probe is used for the measurement of
A. Humidity of air
B. % CO₂ in flue gas
C. % O₂ in flue gas
D. Speed of a submarine
Question 48
The open loop transfer function of a control system is KR/(1 + TS) . This represents
A. A first order system
B. Dead time system
C. A first order time lag
D. A second order system
Question 49
Response of a linear control system for a change in set point is called
A. Frequency response
B. Transient response
C. Servo problem
D. Regulator problem
Question 50
__________ is undesirable in thermocouples used in industries,
A. Linear relation of emf to temperature
B. Corrosion resistance
C. Oxidation resistance
D. Non-linear relation of emf to temperature
Question 51
Measurement of pressure in ammonia reactor is done by
A. Bourdon gauge
B. U-tube manometer
C. Inclined tube manometer
D. Pirani guage
Question 52
Composition of alloys can be determined by
A. Polarograph
B. Chromatograph
C. Refractrometer
D. None of these
Question 53
Optical activity of a solution can be determined using a
A. Polarimeter
B. Polarograph
C. Dilatometer
D. Refractrometer
Question 54
The initial value (t=0) of the unit step response of the transfer function [(s + 1)/(2s + 1)] is
A. 0
B. 1-2
C. 1
D. 2
Question 55
Temperature measurement range of iron-constantan thermocouple is 0 to 870°C. It can be used to measure sub zero temperature, because at lower temperature
A. Emf produced is very low of the order of microvolt
B. Embrittlement of iron occurs
C. Rusting of iron takes place
D. Both B and C
Question 56
In a single tank system, the transfer function of __________ to inlet flow rate is 1/TS+1.
A. Outlet flow rate
B. Level
C. Both A & B
D. Neither A nor B
Question 57
Pick out the wrong statement
A. Proportional controller is normally used for level control in industrial applications
B. CSTR can be considered as a distributed parameter system
C. Distributed parameter approach gives partial differential equation
D. Non-linear behaviour is exemplified by an on-off controller
Question 58
Stabilising time for the controllers is the time required for the response to reach __________ percent of its ultimate value.
A. 63.2
B. 87.5
C. 95
D. 100
Question 59
Which of the following controllers has the least maximum deviation?
A. P-controller
B. P-I controller
C. P-I-D controller
D. P-D controller
Question 60
The time constant of a unity gain, first order plus time delay process is 5 min. If the phase lag at a frequency of 0.2 rad/min is 60°, then the dead time (in minutes) is
A. 5π/12
B. π/6
C. π/12
D. π/3
Question 61
Suppose that the gain, time constant and dead time of a process with the following transfer function:Gc(s) = 10 exp( - 0.1s)/(0.5s + 1) are known with a possible error of ± 20% of their values. The largest permissible gain Kc of a proportional controller needs to be calculated below taking the values of process gain, time constant and dead time as
A. 8, 0.6, 0.08
B. 12, 0.6, 0.12
C. 8, 0.6, 0.12
D. 12, 0.4, 0.08
Question 62
The amplitude ratio for the sinusoidal response of __________ is < 1.
A. Transportation lag
B. First order system
C. Second order system
D. None of these
Question 63
A bolometer is
A. Used for the measurement of thermal radiation
B. An element which senses optical input and delivers thermal output
C. Both A & B
D. Neither A nor B
Question 64
According to Bode stability criterian, 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°
Question 65
Pick out the most suitable instrument for measuring temperature in the range of-40 to 425°C.
A. Mercury thermometer
B. Bimetallic thermometer
C. Radiation pyrometer
D. None of these
Question 66
Mcleoid gauge is used to measure the
A. Point velocity
B. Flow rate
C. Vacuum
D. Pressure
Question 67
Which of the following can measure temperatures in the range of - 20 to 300°C ?
A. Mercury in glass thermometer
B. Vapor pressure thermometer
C. Resistance thermometer
D. None of these
Question 68
Vapour actuated pressure spring thermometer does not require ambient temperature compensation. Ambient temperature compensation is provided in gas or liquid expansion pressure spring thermometer by
A. Making the volume of thermometer bulb as large as conveniently possible
B. Reducing the volume of the capillary to a minimum
C. Reducing the volume of the receiving element to a minimum
D. All of the above
Question 69
Phase lag of the frequency response of a second order system to a sinusoidal forcing function
A. Is 30°
B. Is 90° at the most
C. Approaches 180° asymptotically
D. Is 120°
Question 70
For measuring the temperature of a red hot furnace, which is the most suitable instrument?
A. Platinum resistance thermometer
B. Thermocouple
C. Optical pyrometer
D. Bimetallic thermometer
Question 71
Pressure of 0.0001 absolute psi can be measured by __________ gauge.
A. Mcloid
B. Pirani
C. Thermocouple
D. None of these
Question 72
A negative gain margin expressed in decibels means a/an __________ system.
A. stable
B. unstable
C. critically damped
D. none of these
Question 73
Which of the following thermometers is not suitable for distant reading upto 60 metres?
A. Vapor pressure thermometer
B. Mercury in glass thermometer
C. Constant volume gas thermometer
D. Resistance thermometer
Question 74
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 e
C. Decay ratio (which is the ratio of the sizes of successive peaks) is equal to the reciprocal of overshoot
D. None of these
Question 75
Which of the following measurements can be made by the measurement of emf ?
A. pH value
B. Degree of hydrolysis
C. Composition of complex ions
D. All (a), (b) & (c)
Question 76
Thermal conductivity cell is the primary element of a/an __________ analyser.
A. Oxygen
B. Carbon dioxide
C. Carbon monoxide
D. Sulphur dioxide
Question 77
Bode diagram is a plot of
A. Log (AR) vs. log (f) and (Φ) vs. log (f)
B. Log (AR) vs. f and log Φ vs.f
C. AR vs. log (f) and Φ vs. log (f)
D. None of these
Question 78
Paramagnetism method is not used for the composition determination of __________ in gases.
A. Oxygen
B. Oxides of nitrogen
C. Carbon dioxide
D. Any of these
Question 79
In Bode plot, Φ vs ω is plotted on a/an __________ graph paper.
A. Log-log
B. Ordinary
C. Semi-log
D. Triangular
Question 80
The maximum service temperature for fibre glass used as thermocouple wire insulation material is __________ °C.
A. 250
B. 500
C. 750
D. 1000
Question 81
A barometer measures the __________ pressure.
A. Absolute
B. Gauge
C. Absolute as well as gauge
D. Dynamic
Question 82
A proportional controller with a gain of Kc is used to control a first order process. The offset will increase, if
A. Kc is reduced.
B. Kc is increased.
C. integral control action is introduced.
D. derivative control action is introduced.
Question 83
Which of the following is not a composition measuring instrument?
A. Thermal conductivity cell
B. Mass spectrometer
C. Polarograph
D. Hot wire anemometer
Question 84
Reference points i.e., ice point and steam point in Reaumer temperature scale are respectively
A. - 273° & 80°
B. 0° & 80°
C. 32° & 460°
D. 32° & 80°
Question 85
Pirani gauge is used for the measurement of
A. Very high pressure
B. High vacuum
C. Liquid level under pressure
D. Liquid level at atmospheric pressure
Question 86
Accurate temperature measurement performance of a radiation pyrometer can not be affected, if the
A. Enhancement or attentuation of redia-tion occurs in the sighting path
B. Object and surrounding are at almost the same temperature
C. Object has varying emissivity
D. Object is transparent
Question 87
Bourdon gauges are used for measuring pressure (kg/cm² )
A. < atmospheric
B. > 2 (gauge)
C. < 2 (gauge)
D. > 10 (absolute)
Question 88
Pressure of 0.01 psi (absolute) can be measured by __________ gauge.
A. Ionisation
B. Pirani
C. Mcloid
D. None of these
Question 89
The second order system with the transfer function 4/(S² + 2S + 4) has a damping ratio of
A. 2
B. 0.5
C. 1
D. 4
Question 90
A photo electric device in which the resistance of the metal is directly proportional to the light striking on it, is known as photo-conductive cell. Photoelectric transducers are used for the measurement of those parameters, which can be used to produce variation in
A. Light intensity
B. Current
C. Flux density
D. Voltage
Question 91
Continuous measurement of moisture in paper is done by
A. Sling psychrometer
B. Hair-hygrometer
C. Weighing
D. High resistance Wheatstone's bridge circuit
Question 92
Which of the following filled system expansion thermometers has the lowest positive temperature measurement capability?
A. Mercury in glass thermometer
B. Alcohol in glass thermometer
C. Fused metal (Na or K) in steel thermometer
D. Nitrogen in steel thermometer
Question 93
Process degree of freedom indicates __________ number of controllers to be used.
A. The maximum
B. The minimum
C. Both maximum and the minimum
D. Nothing about the
Question 94
Use of I-control along with P-control facilitates
A. Elimination of offset
B. Reduction of offset
C. Reduction of stability time
D. None of these
Question 95
__________ type of element is normally not used in the bimetallic thermometers.
A. Flat spiral
B. Bourdon tube
C. Single helix
D. Multiple helix
Question 96
When a bare thermocouple is covered by a protective sheath, the response becomes
A. Faster and oscillatory
B. Faster and non-oscillatory
C. Slower and oscillatory
D. Slower and non-oscillatory
Question 97
__________ thermometer can not measure sub-zero (< 0° C) temperature,
A. Mercury in glass
B. Bimetallic
C. Vapor pressure
D. Resistance
Question 98
What is the dynamic error in a critically damped second order instrument for a ramp input (AT)?
A. 0.5 AT
B. 2 AT
C. √AT
D. 1.5 AT
Question 99
A constant volume gas thermometer employing __________ is used to measure sub-zero (i.e., < 0° C) temperature.
A. Helium
B. Hydrogen
C. Nitrogen
D. None of these
Question 100
The __________ of a vapor pressure thermometer is a secondary element.
A. pointer
B. Bourdon tube
C. bulb
D. none ofthese
Question 101
__________ stability method uses open loop transfer function.
A. Nyquist
B. Mikhalov
C. Ruth
D. None of these
Question 102
The thermal emf-temperature relationship of most thermocouples is
A. Linear
B. Parabolic
C. Exponential
D. Square root
Question 103
Emf generated in a thermocouple depends on the temperature
A. Of cold junction only
B. Of hot junction only
C. Difference between hot and cold junctions
D. Difference between cold junction and atmospheric temperature
Question 104
Bode diagram are generated from output response of the system subjected to which of the following input?
A. Impulse
B. Step
C. Ramp
D. Sinusoidal
Question 105
Which of the following is not classified as a thermo electric pyrometer?
A. Resistance thermometer
B. Thermocouple
C. Optical pyrometer (disappearing filament type)
D. Radiation pyrometer
Question 106
Liquid flow rate in a small channel is best measured by a/an
A. Weir
B. Pitot tube
C. Vane meter
D. Venturimeter
Question 107
For an input forcing function, X(t) = 2t², the Laplace transform of this function is
A. 2/s²
B. 4/s²
C. 2/s³
D. 4/s³
Question 108
An aneroid barometer measures the __________ pressure.
A. Atmospheric
B. Absolute
C. Vacuum
D. Gage
Question 109
Temperature control of an exothermic chemical reaction taking place in a CSTR is done with the help of cooling water flowing in a jacket around the reactor. The types of valve and controller action to be recommended are
A. Air to open valve with the controller direct acting
B. Air to close valve with the controller indirect acting
C. Air to open valve with the controller indirect acting
D. Air to close valve with the controller direct acting
Question 110
Nichol's chart deals with
A. A.R. vs. phase lag of first order.
B. A.R. vs. phase lag of second order.
C. closed loop values vs. open loop values.
D. frequency response values of controllers.
Question 111
A first order system with a time constant of 1 min is subjected to frequency response analysis. At an input frequency of 1 radian/min, the phase shift is
A. 45°
B. -90°
C. -180°
D. -45°
Question 112
Which of the following is never used as an element of industrial resistance thermometer?
A. Lead
B. Nickel
C. Copper
D. 30% iron + 70% nickel
Question 113
Which of the following judges the accuracy of an instrument?
A. Dead zone
B. Drift
C. Static error
D. None of these
Question 114
The transfer function of a first order system is
A. 1/(Ts + 1)
B. 1/Ts
C. S/(Ts + 1)
D. None of these
Question 115
Liquid levels in autocalves are measued by
A. Simple float
B. Differential float type manometer
C. Glass gauge
D. None of these
Question 116
Non-metallic diaphragm used as pressure sensor in instruments is generally made of
A. Teflon
B. Synthetic rubber
C. Bakelite
D. Thick paper
Question 117
Humidity of air can be determined by a
A. Chromatograph
B. Sling psychrometer
C. Mass spectrometer
D. Polarimeter
Question 118
__________ temperature scale assigns 0° to the 'ice point' and 80° to the 'steam point'.
A. Celcius
B. Rankine
C. Reumur
D. Farenhite
Question 119
Relationship between absorption/evolution of heat at the thermocouple junctions and the current flow in the circuit is given by __________ effect.
A. Peltier
B. Thomson
C. Seebeck
D. None of these
Question 120
The closed loop pole of a stable second order system could be
A. both real and positive.
B. complex conjugate with positive real parts.
C. both real and negative.
D. one real positive and the other real negative.
Question 121
If response of a control system is to be free of offset and oscillation, the most suitable controller is
A. Proportional controller
B. Proportional-derivative(PD)controller
C. Proportional-integral (PI) controller
D. Proportional integral-derivative (PID) controller
Question 122
Mercury thermometer is commonly used for low temperature measruement. The freezing point and boiling point of mercury are respectively __________ °C.
A. - 39 and 350
B. - 51 and 439
C. - 79 and 395
D. - 10 and 425
Question 123
What is the normal percentage of rhodium in platinum + rhodium element used in the thermocouple?
A. 0.1
B. 3
C. 13
D. 29
Question 124
Volumetric expansion is the working principle of the __________ thermometers.
A. mercury in glass
B. constant volume gas
C. vapor pressure
D. bimetallic
Question 125
A first order system with unity gain and time constant τ is subjected to a sinusoidal input of frequency w = 1/τ. The amplitude ratio for this system is
A. 1
B. 0.5
C. 1/√2
D. 0.25
Question 126
Which of the following thermocouples is the most suitable for measuring a temperature of about 1600°C in an oxidizing atmosphere?
A. Platinum-platinum + rhodium
B. Iron-constantan
C. Copper-constantan
D. Chromel-alumel
Question 127
Liquid discharge from a tank or reservoir can not be measured by
A. Orificemeters
B. Weirs
C. Mouthpieces
D. Notches
Question 128
Instrumentation in a plant offers the advantage of
A. greater safety of operation
B. better quality of product
C. greater operation economy
D. all (a), (b) and (c)
Question 129
Hot wire anemometer is used for the measurement of
A. Flow rates of fluids
B. Flow rates of granular solids
C. Very high temperature
D. Thermal conductivity of gases
Question 130
Photoelectric pyrometers are suitable in the temperature range of __________ °C.
A. 400-1600
B. 800-1600
C. 800-2500
D. 400-1000
Question 131
The term analogous to the electrical current in a thermal system is the
A. Temperature difference
B. Heat flow rate
C. Heat content in the system
D. None of these
Question 132
The unit of 'time constant' of a system is the same as that of
A. Velocity
B. Time
C. (time)⁻¹
D. None of these
Question 133
Working principle of radiation pyrometer is based on the
A. Wien's law
B. Kirchoffs law
C. Stafan-Boltzman law
D. Seebeck effect
Question 134
Nichol's chart deals with
A. A.R. vs. phase lag of first order
B. A.R. vs. phase lag of second order
C. Closed loop values vs. open loop values
D. Frequency response values of controllers
Question 135
Radiation pyrometers as compared to thermocouples
A. Has a slower speed of response
B. Can measure higher temperature
C. Can't measure the temperature of moving objects
D. Is more affected by corrosive atmosphere
Question 136
Stroboscope is used for the measurement of
A. Rpm of a flywheel
B. Frequency of light
C. Depression of freezing point
D. Liquid level under pressure
Question 137
The transfer function of a pure dead time system with dead time τd is
A. 1/(τds + 1)
B. Τds + 1
C. E-τds
D. Eτds
Question 138
__________ controller has the maximum stabilising time.
A. P
B. PD
C. PI
D. PID
Question 139
For two non-interacting first order systems connected in series, the overall transfer function is the __________ of the individual transfer functions.
A. Product
B. Ratio
C. Sum
D. Difference
Question 140
Silver point temperature is __________ °C.
A. 760.5
B. 860.5
C. 960.5
D. 1060.5
Question 141
A system with transfer function (2S/4S) + 1 is of __________ order.
A. Zero
B. 1st
C. 2nd
D. 3rd
Question 142
0n-off control which is a special case of proportional control, has a band width of about __________ percent.
A. 100
B. 75
C. 25
D. 0
Question 143
Pick out the wrong statement.
A. There is no transfer lag for a single first order system
B. Stirred tank with a water jacket exemplifies an interacting system
C. Transfer lag is a characteristics of all higher order systems (other than first order systems)
D. Transfer lag decreases as the number of stages decreases
Question 144
The deflection in diaphragm (which is used as pressure sensor in pneumatic and electronic instruments) is dependent on the metal thickness, its diameter (d) and shape & number of corrugations. Its deflection is proportional to
A. D
B. D²
C. D³
D. D⁴
Question 145
The function of a transducer is to
A. Modify the input signal
B. Amplify the input signal
C. Convert the primary signal into a more useful quantity, usually an electric impulse
D. Codify/decodify the input signal
Question 146
Which of the following does not figure in the list of seven substances selected for international temperature scale?
A. Ice (F.P) and steam (B.P)
B. Oxygen and sulphur (B.P)
C. Antimony and silver (F.P)
D. Zinc (B.P) and mercury (F.P)
Question 147
Starting temperature of optical radiation pyrometer is __________ °C.
A. 800
B. 400
C. 1200
D. 1500
Question 148
Which of the following is not a second order instrument?
A. Mercury in glass thermometer with covering
B. Bare mercury in glass thermometer
C. Pressure gauge with one bellow, two tubes and a tank
D. None of these
Question 149
Thermal conductivity measurement com-prises the working principle of a
A. CO₂ analyser
B. Polarimeter
C. Spectrometer
D. Chromatograph
Question 150
Presence of a small amount of water in the organic systems can be determined by the __________ method.
A. Electrical conductivity
B. Polarimetry
C. Emission spectroscopy
D. Dielectric constant end loss factor
Question 151
Phase margin is equal to
A. 180° - phase lag
B. Phase lag - 180°
C. Phase lag + 180°
D. Phase lag + 90°
Question 152
A manometer measures the __________ pressure.
A. Atmospheric
B. Absolute
C. Gauge
D. None of these
Question 153
Emf developed by a thermocouple, while measuring a temperature of 600°C is about 5.5 mV. The type of thermocouple used is
A. chromel-alumel
B. iron-constantan
C. platinum-platinum+rhodium
D. either (a), (b) or (c)
Question 154
Which of the following thermocouples has the least temperature measurement range?
A. Copper-constantan
B. Chromel-alumel
C. Platinum-platinum/rhodium
D. Iron-constantan
Question 155
Which of the following is a desirable characteristic of an instrument?
A. High drift
B. High fidelity
C. High measuring lag
D. Poor reproducibility
Question 156
Mass spectrometer is used for the composition analysis of
A. Alloys
B. Solids
C. Isotopes
D. None of these
Question 157
Thermocouple in a thermal well behaves as a true
A. First order system
B. Second order system (overdamped)
C. Multiple first order system
D. Second order system (underdamped)
Question 158
Emf developed by a thermocouple, while measuring a temperature of 600°C is about 5.5 mV. The type of thermocouple used is
A. Chromel-alumel
B. Iron-constantan
C. Platinum-platinum+rhodium
D. Either A, B or C
Question 159
Number of poles in a system with transfer function 1/(s² + 2s² + 1) is
A. 2
B. 5
C. 3
D. 1
Question 160
Pick out the one which is a first order instrument.
A. Mercury in glass thermometer (without any covering or air gap)
B. Bare metallic thermometer
C. Bare vapor pressure thermometer
D. All of the above
Question 161
A non-linear chemical system is exemplified by a/an
A. Isothermal CSTR
B. Mixer
C. Non-isothermal CSTR
D. None of these
Question 162
A mercury barometer measures the __________ pressure.
A. Atmospheric
B. Gauge
C. Vacuum
D. Absolute
Question 163
Which of the following is not the triple point of water ?
A. 32°R
B. 273°K
C. 492°R
D. 32°F
Question 164
Gas chromatography is used for the measurement of
A. Temperature
B. Pressure
C. Concentration
D. Flow rate
Question 165
The __________ of a vapor pressure thermometer is a primary element.
A. Pointer
B. Bourdon tube
C. Bulb
D. None of these
Question 166
Flow rate through an orifice is __________ the pressure differential.
A. Proportional to
B. Inversely proportional to the square root of
C. Proportional to the square root of
D. Inversely proportional to the square of
Question 167
The __________ of the fluid contained in the temperature sensing element (i.e., bulb) of filled system thermometers changes with change in temperature.
A. Pressure
B. Volume
C. Viscosity
D. All of the above
Question 168
Load cells are used for the measurement of
A. stress
B. weight
C. strain
D. velocity
Question 169
The transfer function for a P-D controller is
A. Kc(1+τD s)
B. Kc(1 +1/τD s)
C. Kc τD s
D. Kc/τD s
Question 170
Sub-zero temperature (< 0°C) can be measured by a constant volume gas thermometer employing
A. Helium
B. Nitrogen
C. Hydrogen
D. None of these
Question 171
Degree to which an instrument indicates the changes in measured variable without dynamic error is called its
A. Speed of response
B. Reproducibility
C. Fidielity
D. Static characteristics
Question 172
All the thermocouples used for temperature measurement use dissimilar metal
A. Strips
B. Bars
C. Wires
D. Beads
Question 173
In a shell and tube heat exchanger, the flow rate of heating/cooling fluid is the __________ variable.
A. load
B. controlled
C. manipulated
D. none of these
Question 174
Which of the following relates the absorption & evolution of heat at the junctions of a thermocouple to the current flow in the circuit?
A. Seebeck effect
B. Peltier effect
C. Joule heating effect
D. Thomson effect
Question 175
Temperature measuring instruments are standardised mostly with __________ points of pure substances.
A. Melting
B. Boiling
C. Both A & B
D. Neither A nor B
Question 176
Thermisters 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
Question 177
In a shell and tube heat exchanger, the outlet temperature of heating/cooling fluid is the __________ variable.
A. Load
B. Manipulated
C. Controlled
D. None of these
Question 178
In an exothermic chemical reactor, the manipulated variable is the flow rate of
A. Coolant
B. Reactants
C. Product
D. None of these
Question 179
Thermal well made of __________ gives the fastest speed of response, while measuring temperature by thermocouples.
A. Steel
B. Vycor (a glass)
C. Nichrome
D. Inconel
Question 180
Range of hydrogen gas constant volume themometer is __________ °C.
A. -10 to 20
B. 0 to 100
C. 100 - 500
D. 400 - 1000
Question 181
Compositional analysis of __________ is done using mass spectrometer.
A. an isotope
B. natural gas
C. a solid
D. an alloy
Question 182
Dead zone is the
A. Same as time constant
B. Same as transportation lag
C. Maximum change in the variable that does not change the reading of the instrument
D. None of these
Question 183
Which of the following is the dynamic characteristics of an instrument ?
A. Reproducibility
B. Sensitivity
C. Dead zone
D. Fidelity
Question 184
Out of the following temperature measuring instruments, the measurement accuracy will be minimum for the
A. Mercury in glass thermometer
B. Optical pyrometer
C. Iron-constantan thermocouple
D. Alcohol filled thermometer
Question 185
A control system has the following transfer function F(s) = (s - 1)(s + 1)/s(s - 2)(s + 4)The initial value of the corresponding time function is
A. 1
B. 1-8
C. 7-8
D. -1
Question 186
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
Question 187
A pyrheliometer is an instrument used for measuring the
A. Bright sunshine period
B. Beam radiation
C. Diffuse radiation
D. None of these
Question 188
In a closed loop system, the process to be controlled is an integrating process with transfer function l/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
Question 189
Feed forward controller accounts for the __________ changes.
A. Set point
B. Load
C. Both A & B
D. Neither A nor B
Question 190
Zirconia probe is used for the continuous measurment of __________ flue gases going out of the furnace.
A. oxygen in
B. carbon dioxide in
C. carbon monoxide in
D. temperature of
Question 191
On-off controllers are normally used for
A. Low loads
B. Temperature changes
C. Flow rate changes
D. None of these
Question 192
A magnetic flowmeter is
A. Based on the principle of Faraday's law
B. Capable of measuring the flow rate of slurries and electrolytes
C. Based on the linear relationship between the fluid flow rate and the induced voltage
D. All of the above
Question 193
Which of the following controllers has the least maximum deviation ?
A. P-controller
B. P-I controller
C. P-I-D controller
D. P-D controller
Question 194
The Laplace transform of exp(at), where a > 0, is defined only for the Laplace parameter, s > a since
A. The function is exponential
B. The Laplace transform of integral of exp(at) has finite values only for s > a
C. The Laplace transform integral of exp(at) has initial values only for s > a
D. The function exp(at) is piece-wise continuous only for s > a
Question 195
The operation of a rotameter is based on
A. variable flow area.
B. rotation of a turbine.
C. pressure drop across a nozzle.
D. pressure at a stagnation point.
Question 196
Flow rate of sludge is not measured by a/an
A. Orificemeter
B. Open weir
C. Kennison nozzle
D. Both B & C
Question 197
What is the ratio of output amplitude to input amplitude for a sinusoidal forcing function in a first order system?
A. 1
B. >1
C. < 1
D. None of these
Question 198
Which of the following temperature measuring instruments need not touch the object whose temperature is being measured?
A. Radiation/infrared pyrometer
B. Filled system thermometer
C. Mercury in glass thermometer
D. Thermo electric pyrometer
Question 199
The root locus plot of the roots of the characteristics equation of a closed loop system having the open loop transfer function K(s + 1)/2(2s + 1)(3s + 1) will have a definite number of loci for variation of K from 0 to ∞. The number of loci is
A. 1
B. 3
C. 4
D. 2
Question 200
Which of the following thermocouples is incapable of measuring sub-zero (i.e., < 0°C) temperature?
A. Chromel-alumel
B. Iron-constantan
C. Platinum-platinum + rhodium
D. Copper-constantan
Question 201
For an input forcing function, X(t) = 2t2, the Laplace transform of this function is
A. 2/s2
B. 4/s2
C. 2/s3
D. 4/s3
Question 202
Liquid flow rate in an open channel can not be measured by a/an
A. Orifice meter
B. Cipolletti weir
C. Rectangular weir
D. V-notch
Question 203
Liquid argon level in a pressurised storage tank (at 3 kg/cm² ) is measured by a/an
A. Gage glass
B. External float gage
C. Differential pressure gage
D. None of these
Question 204
An emf of the order of mV is generated when two solutions of different hydrogen ion concentration are separated by a thin glass wall. This is the working principle of a
A. PH meter
B. Polarimeter
C. Chromatograph
D. Polarograph
Question 205
Measurement of sub-zero Celcius temperature in industry is done most commonly by
A. Thermocouples
B. Resistance thermometers
C. Gas thermometers
D. Bi-metallic thermometers
Question 206
Which of the following is the dynamic characteristics of an instrument?
A. Reproducibility
B. Sensitivity
C. Dead zone
D. Fidelity
Question 207
The fluid used in hydraulic controller is
A. Water
B. Steam
C. Air
D. Oil
Question 208
Liquid column manometers are used for measuring the pressure __________ kgf/cm² .
A. > 2(gage)
B. < 3 (gage)
C. < 10 (gage)
D. < atmospheric
Question 209
Dead zone in an instrument must be less than __________ percent of the scale.
A. 0.2
B. 1.5
C. 4
D. 8
Question 210
Which of the following is not a variable area flow meter?
A. Piston type meter
B. Rotameter
C. Magnetic flow meter
D. Orifice and tapered plug meter
Question 211
Cascade control means
A. Feed forward control
B. More than one feed-back loop
C. On-off control
D. One feed-back loop
Question 212
Phase lag of the sinusoidal response of a first order system is
A. 120°
B. 30°
C. 180°
D. 90°
Question 213
Pick out the wrong statement.
A. O₂, NO and NO₂ exhibit paramagnetic properties as a result of unpaired electrons
B. CO₂ is the strongest paramagnetic gas
C. Paramagnetic susceptibility of gases decreases with temperature
D. Paramagnetic susceptibility of gases permits the measurement of their concentration
Question 214
The closed loop pole of a stable second order system could be
A. Both real and positive
B. Complex conjugate with positive real parts
C. Both real and negative
D. One real positive and the other real negative
Question 215
A bimetallic thermometer as compared to industrial mercury in glass thermometer has almost the same
A. Temperature measuring range (- 40°C to 450°C)
B. Accuracy (± 1% of span)
C. Speed of response
D. All of the above
Question 216
Transfer function of transportation lag is
A. ETS
B. E-TS
C. 1/(TS + 1)
D. None of these
Question 217
__________ are analysed using a polarograph.
A. Isotonic solutions
B. Solids
C. Liquids
D. Gases
Question 218
Dome temperature of blast furnace stove is most accurately measured by a
A. Radiation pyrometer
B. Platinum-platinum/rhodium ther-mocuple
C. Iron-constantan thermocouple
D. Platinum resistance thermometer
Question 219
Find the ultimate gain and frequency for a proportional controller in the case of a process having the transfer function Gp(s) = 1/(4s + 1)(2s + 1)(s + 1).
A. W = 1/√14, Kc = 45/7√14
B. W = √(7/6), Kc = 46/3
C. W = 1, Kc = 13
D. W = √(7/8), Kc = 45/4
Question 220
The root locus method, a pole of a transfer function G(s) is the value of s for which G(s) approaches
A. -1
B. 0
C. 1
D. ∞
Question 221
Pick out the one which is a first order instrument.
A. Mercury in glass thermometer (without any covering or air gap).
B. Bare metallic thermometer.
C. Bare vapor pressure thermometer.
D. All (a), (b) and (c).
Question 222
Which is the most suitable instrument for measuring pressure below 3 microns?
A. Mcleoid gauge
B. Alphatron
C. Ionisation gauge
D. Bourdon guage
Question 223
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
Question 224
Minute depression of freezing point of a liquid solvent on addition of a solid solute can be best measured by a
A. Beckman thermometer
B. Dilatometer
C. Mercury thermometer
D. Bimetallic thermometer
Question 225
The frequency response of a first order system, has a phase shift with lower and upper bounds given by
A. - ∞, π/2
B. -π/2, π/2
C. -π/2, 0
D. 0, π/2
Question 226
Which is the strongest paramagnetic gas?
A. CO₂
B. O₂
C. NO
D. NO₂
Question 227
In a shell and tube heat exchanger, the inlet temperature of heating/cooling fluid is the __________ variable.
A. Load
B. Manipulated
C. Controlled
D. None of these
Question 228
Which of the following flow-metering instru-ments is an areameter?
A. Venturimeter
B. Rotameter
C. Pitot tube
D. Hot wire anemometer
Question 229
Transfer function of transportation lag is
A. eTS
B. e-TS
Question 230
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
Question 231
Conversion formula for converting amplitude ratio (AR) into decibels is
A. Decibel = 20 log10 (AR)
B. Decibel = 20 loge (AR)
C. Decibel = 20 log10 (AR)0.5
D. Decibel = 20 loge (AR)0.5
Question 232
Alphatron measures pressure __________ microns.
A. < 1
B. < 3
C. > 3
D. < 0.1
Question 233
Out of the following themocouple wire insulating material, the highest temperature rating is for
A. Teflon
B. Ceramic fibre
C. Asbestos
D. Fibre glass
Question 234
A stable system is the one
A. For which the output response is bounded for all bounded input
B. Which exhibits an unbounded response to a bounded input
C. Which satisfies the conditions for a servo problem
D. None of these
Question 235
Emission spectroscopy is used for
A. Solids and metal analysis
B. Determining water purity
C. Determination of CO₂ in gases
D. NOxdetermination
Question 236
Gain margin is equal to the
A. Amplitude ratio
B. Reciprocal of amplitude ratio
C. Gain in P controller
D. Gain in P-I controller
Question 237
The inverse Laplace transform of the function f(s) = 1/S(1 + S) is
A. 1 + et
B. 1 - et
C. 1 + e-t
D. 1 - e-t
Question 238
The operation of a rotameter is based on
A. Variable flow area
B. Rotation of a turbine
C. Pressure drop across a nozzle
D. Pressure at a stagnation point
Question 239
Which of the following is not a speed measuring instrument?
A. Psychrometer
B. Stroboscope
C. Tachometer
D. All of the above
Question 240
In Bode plot, A.R. vs. w is plotted on a/an __________ graph paper.
A. Log-lag
B. Triangular
C. Ordinary
D. Semi-log
Question 241
With increase in temperature, the electrical conductivity of the platinum used in the resistance thermometer
A. Increases
B. Decreases
C. Remains constant
D. Increases exponentially
Question 242
The temperature range for which copper resistance thermometer can be used is __________ °C
A. 0 to 150
B. -200 to 150
C. 350 to 750
D. 500 to 900
Question 243
Platinum resistance thermometer is the international standard for temperature measurement between
A. Triple point of hydrogen and freezing point of antimony
B. 13.81°K to 903.9°K
C. Both A and B
D. Neither A nor B
Question 244
The __________ of a vapor pressure thermometer is a functioning element.
A. pointer
B. bourdon tube
C. bulb
D. none of these
Question 245
The pressure sensing element of elastic type pressure gauge is never made in the form of a
A. Bellow
B. Diaphragm
C. Strip
D. Bourdon tube
Question 246
Flame photometry is used for the determination of compositional analysis of
A. Solids
B. Alkali metals
C. Natural gas
D. Isotopes
Question 247
Concentration of sugar solution can be determined by the
A. Polarimetry
B. Flame photometry
C. Emission spectroscopy
D. Oscillometry
Question 248
Bourdon tube is never made of
A. Phosphor bronze
B. Monel metal
C. Stainless steel
D. Cast iron
Question 249
Typical specifications for design stipulates the gain margin and phase margin to be respectively
A. > 1.7 and > 30°
B. < 1.7 and > 30°
C. < 1.7 and < 30°
D. > 1.7 and < 30°
Question 250
Temperature measuring instruments are standardised mostly with __________ points of pure substances.
A. melting
B. boiling
C. both (a) & (b)
D. neither (a) nor (b)
Question 251
Which of the following is a desirable characteristic of an instrument ?
A. High drift
B. High fidelity
C. High measuring lag
D. Poor reproducibility
Question 252
Thermal conductivity based continuous flue gas analyser makes use of varying thermal conductivity of the constituents of flue gases. Which of the following constituents of flue gases has the maximum thermal conductivity?
A. CO₂
B. N₂
C. O₂
D. CO
Question 253
Identify an unbounded input from inputs whose transfer functions are given below
A. 1
B. 1/S
C. 1/S²
D. 1/(S² + 1)
Question 254
The frequency at which maximum amplitude ratio is attained is called the __________ frequency.
A. Corner
B. Resonant
C. Cross-over
D. Natural
Question 255
When the damping co-efficient (ξ) is unity, the system is
A. Overdamped
B. Critically damped
C. Underdamped
D. Highly fluctuating
Question 256
Mercury manometer (U-tube type) exemplifies a __________ order system.
A. Zero
B. First
C. Second
D. Third
Question 257
Pick out the first order system from among the following.
A. Damped vibrator
B. Mercury in glass thermometer kept in boiling water
C. Interacting system of two tanks in series
D. Non-interacting system of two tanks in series
Question 258
For increased speed of response of an expansion pressure spring thermometer, the thermometer bulb should have a
A. Large area but small mass
B. High thermal conductivity
C. Small specific heat
D. All of the above
Question 259
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 of the above
Question 260
Which of the following temperature measuring instruments need not touch the object whose temperature is being measured ?
A. Radiation/infrared pyrometer
B. Filled system thermometer
C. Mercury in glass thermometer
D. Thermo electric pyrometer
Question 261
__________ is the static characteristics of an instrument,
A. Response
B. Tine lag
C. Drift
D. Dynamic error
Question 262
The transfer function of a process is 1/(16s² + 8s + 4). If a step change is introduced into the system, then the response will be
A. Under damped
B. Critically damped
C. Over damped
D. None of these
Question 263
The term analogous to voltage in a single tank system is the
A. Heat content of the system
B. Liquid volume in the tank
C. Flow rate
D. Level of liquid
Question 264
Thermal conductivity measurement is used for the determination of
A. O₂ percentage in the flue gas
B. Specific gravity of petrofuels
C. Composition of an alloy
D. CO₂ percentage in the flue gas
Question 265
Time constant is the
A. Time taken by the controlled variable to reach 63.2% of its full change
B. Same as transportation lag
C. Same as dead time
D. Time required by the measured variable to reach 63.2% of its ultimate change
Question 266
In second order underdamped system,
A. Decay ratio = overshoot
B. Decay ratio = (overshoot)²
C. Overshoot increases for increasing damping co-efficient
D. Large damping co-efficient means smaller damping
Question 267
Which of the following shows maximum dip effect (indicating reverse direction of temperature change)?
A. Mercury thermometer
B. Radiation pyrometer
C. Bimetallic thermometer
D. Thermocouple
Question 268
Emf developed by a thermocouple while measuring a temperature of 800°C is about 31 mV. The type of thermocouple used is
A. Chromel-alumel
B. Iron-constantan
C. Platinum-platinum+rhodium
D. None of these
Question 269
High temperature of around 2000°C of incandescent gas mantles is measured by a/an
A. Specially designed thermocouple
B. Optical pyrometer
C. Radiation pyrometer
D. None of these
Question 270
A simple pitot tube measures the
A. Average velocity
B. Maximum velocity
C. Point velocity
D. Static pressure
Question 271
Stalagmometer is used for the measurement of
A. Kinematic viscosity
B. Surface tension
C. Refractive index
D. Optical activity
Question 272
Which of the following thermocouples will give the highest output for the same value of hot and cold junction temperature?
A. Platinum-platinum + rhodium
B. Iron-constantan
C. Chromel-constantan
D. All of the above
Question 273
In a single tank system, the transfer function of level to inlet flow rate is
A. R/TS
B. R/(TS + 1)
C. l(TS + l)
D. 1/TS
Question 274
Which of the systems having following transfer functions is stable?
A. 1/(s²+ 2)
B. 1/(s²-2s + 3)
C. 1/(s² + 2s + 2)
D. Exp(-20s)/(s² + 2s-l)
Question 275
What is the Laplace transform of sin t ?
A. 1/(s² + 1)
B. S/(s² + 1)
C. 1/(s² - 1)
D. S/(s² - 1)
Question 276
Thermal wells used in temperature measurements should have
A. Very thick walls
B. Low emissivity
C. Polished surface
D. High transmissivity of radiation
Question 277
The deflection of the free end of the bimetallic strips in a bimetallic thermometer with temperature is nearly
A. Linear
B. Non-linear
C. Parabolic
D. Hyperbolic
Question 278
Flapper nozzle is used in a/an __________ controller.
A. electronic
B. hydraulic
C. pneumatic
D. none of these
Question 279
Continuous measurement of specific gravity of a liquid is done by
A. Hydrometer
B. Contact-type electric indicators
C. Displacement meter
D. Both A and C
Question 280
Helium gas constant volume thermometer is suitable for the measurement of a temperature of __________ °C.
A. < 100
B. < 0
C. > 0
D. > 800
Question 281
Flow rate of a river is measured by a/an
A. Pitot tube
B. Vane meter
C. Kennison nozzle
D. Open weir
Question 282
Pick out the wrong statement.
A. O2, NO and NO2 exhibit paramagnetic properties as a result of unpaired electrons.
B. CO2 is the strongest paramagnetic gas.
C. Paramagnetic susceptibility of gases decreases with temperature.
D. Paramagnetic susceptibility of gases permits the measurement of their concentration.
Question 283
Bode stability method uses __________ loop transfer function.
A. Open
B. Closed
C. Either A or B
D. Neither A nor B
Question 284
Thermodynamic celcius scale of temperature measurement is
A. Defined on the basis of melting point of ice and evaporation temperature of water vapor
B. Defined on the basis of melting point of ice and condensation temperature of water vapor
C. Having an interval of 100° between ice point to steam point
D. Both B and C
Question 285
Specific gravity of a liquid can not be measured by a/an
A. Anemometer
B. Specific gravity bottle
C. Pycnometer
D. Hydrometer
Question 286
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
Question 287
Which of the following is not a mechanical pressure sensing element?
A. Bellows
B. Diaphragm
C. Bourdon tube
D. U-tube
Question 288
The amplitude ratio for the sinusoidal response of a __________ is 1.
A. First order system
B. Second order system
C. Transportation lag
D. None of these
Question 289
Dilute wine was used as a thermometric liquid initially to develop temperature scale. First emperical temperature scale developed was the __________ scale.
A. Kelvin
B. Centigrade
C. Fahrenheit
D. Reaumer
Question 290
Thermal wells are used in the temperature measurement to
A. Guard against corrosive and oxidising action on thermocouple materials
B. Reduce measuring lag
C. Increase the fidelity
D. Increase the sensitivity
Question 291
Thermocouple is suitable for measuring
A. Liquid temperatures only
B. Very high temperatures only
C. Very low temperatures only
D. Both high and low temperatures
Question 292
Reset rate is the another term used for __________ time.
A. Dead
B. Integral
C. Derivative
D. None of these
Question 293
The characteristic equation for the control system with a closed loop transfer function G₁/1 + G₂ is given by 1 + G₂ = 0. The characteristic equation for the control system
A. Depends only upon the open loop transfer function
B. Determines its stability
C. Is the same for set point or load changes
D. All of the above
Question 294
Thermistors are made of
A. Ultra pure metals
B. Metal oxides
C. Iron-copper alloys
D. Nickel-chromium alloys
Question 295
The unit step response of the transfer function 1/(s² + 2s + 3)
A. Has a non-zero slope at the origin
B. Has a damped oscillatory characteristics
C. Is overdamped
D. Is unstable
Question 296
An amplitude ratio of 0.1 corresponds to __________ decibels.
A. 20
B. -20
C. 10
D. -10
Question 297
Nickel percentage in invar which is an iron-nickel alloy, and is used as a thermocouple material is
A. 12
B. 36
C. 54
D. 68
Question 298
A non-linear system will have __________ steady state values.
A. One
B. More than one
C. Two
D. Three
Question 299
Which of the following is an undesirable dynamic characteristic of an instrument?
A. Reproducibility
B. Dead zone
C. Time lag
D. Static error
Question 300
Which of the following relates the emf. generated in a single homogeneous wire to the temperature difference ?
A. Peltier effect
B. Thomson effect
C. Seebeck effect
D. none of these
Question 301
The function of a transducer is to
A. modify the input signal.
B. amplify the input signal.
C. convert the primary signal into a more useful quantity, usually an electric impulse.
D. codify/decodify the input signal.
Question 302
Specific conductance is defined as the reciprocal of resistance in ohms of 1c.c. of liquid at a specified temperature. Its value for distilled water is about __________ micro mho/cm³.
A. 50
B. 100
C. 10
D. 1
Question 303
Continuous shell temperature measurement in a liquid-liquid heat exchanger is done by a
A. thermocouple
B. reistance thermometer
C. mercury in glass thermometer
D. vapor pressure thermometer
Question 304
Small furnace draught is accurately measured by an inclined tube manometer, in which the manometric liquid used most commonly is
A. Water
B. Carbon tetrachloride
C. Paraffin
D. Ethylene glycol
Question 305
Radiation thermometer can not measure the temperature
A. Inside a pressure vessel
B. Of an object without coming in contact with it
C. Of liquid oxygen
D. Of moving objects at high temperature
Question 306
The time constant of a first order process with resistance R and capacitance C is
A. R + C
B. R - C
C. RC
D. 1/RC
Question 307
Thermal conductivity measurement com-prises the working principle of a
A. CO2 analyser
B. polarimeter
C. spectrometer
D. chromatograph
Question 308
E.m.f. generated by thermocouples is of the order of
A. Millivolts
B. Microvolts
C. Volts
D. Kilo volts
Question 309
Dilatometer is used to measure
A. Stress
B. Strain
C. Deflection
D. Contraction/expansion due to changes in temperature
Question 310
Select the correct statement from the following.
A. The frequency response of a pure capacity process is unbounded
B. The phase lag of a pure time delay system decreases with increasing frequency
C. The amplitude ratio of a pure capacity process is inversely proportional to frequency
D. The amplitude ratio of a pure time delay system increases with frequency
Question 311
A mercury thermometer can not be used to measure the temperature below the freezing point of mercury, which is __________ °C.
A. -38.9
B. -11.9
C. -60.9
D. -80.9
Question 312
Strain gage uses an electrical conductor wire, which when elastically stretched increases in length and reduces in diameter. Both these dimensional changes result in __________ in the electrical resistance of the wire.
A. No change
B. Decrease
C. Increase
D. Exponential decrease
Question 313
The temperature of tempering oil baths maintained at 400°C during heat treatment of steel is measured by a/an __________ thermocouple.
A. Chromel-alumel
B. Iron-constantan
C. Platinum-platinum/rhodium
D. None of these
Question 314
Working principle of mercury in glass thermometer is based on the __________ of mercury with increase in temperature.
A. Increase of pressure
B. Increase of thermal conductivity
C. Volumetric expansion
D. Differential linear expansion
Question 315
In a feed-back control system G and H denote open loop and close loop transfer functions respectively. The output-input relationship is
A. G/(1 + H)
B. H(1 + G)
C. G/H
D. H/G
Question 316
Bimetal strips are not used in
A. Bimetallic thermometers
B. Thermocouples
C. Thermostats
D. Relays for opening & closing of electrical circuits
Question 317
Strain gage pressure transducers are used to measure __________ pressures.
A. Gage as well as vacuum
B. Absolute as well as differential
C. Both A & B
D. Neither A nor B
Question 318
Which of the following is an undesirable dynamic characteristic of an instrument ?
A. Reproducibility
B. Dead zone
C. Time lag
D. Static error
Question 319
Normal mercury thermometer can be used to measure a temperature of about 300°C. However, its maximum temperature measurement range can be increased upto about 500°C by
A. Filling nitrogen under pressure in the stem
B. Increasing the diameter of the tube
C. Using steel tube in place of glass tube
D. Accounting for the tube expansion
Question 320
Instrumentation in a plant offers the advantage of
A. Greater safety of operation
B. Better quality of product
C. Greater operation economy
D. All of the above
Question 321
Continuous flue gas analyser makes use of paramagnetic properties of some of its constituents, which move towards the strongest part of the magnetic field thus displacing diamagnetic gases. Which of the following gases is diamagnetic?
A. CO₂
B. O₂
C. NO
D. NO₂
Question 322
A magnetic flowmeter is
A. based on the principle of Faraday's law.
B. capable of measuring the flow rate of slurries and electrolytes.
C. based on the linear relationship between the fluid flow rate and the induced voltage.
D. all (a), (b) and (c).
Question 323
A sinusoidal variation in the input passing through a linear first order system
A. Becomes more oscillatory (frequency increases)
B. Becomes less oscillatory (frequency decreases)
C. Gets amplified (magnitude increases)
D. Gets attenuated (magnitude decreases)
Question 324
Polarisation of light forms the working principle of a
A. Polarimeter
B. Polarograph
C. Chromatograph
D. Spectrometer
Question 325
Which of the following thermocouple materials does not contain nickel?
A. Alumel
B. Chromel
C. Constantan
D. None of these
Question 326
Working principle of mercury in glass thermometer is based on volumetric expansion of mercury with increase in temperature. Which of the following undergoes minimum volumetric expansion for a given temperature change?
A. Water
B. Mercury
C. Methyl alcohal
D. Carbon-tetrachloride
Question 327
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
Question 328
Which of the following measurements can be made by the measurement of emf?
A. PH value
B. Degree of hydrolysis
C. Composition of complex ions
D. All of the above
Question 329
Strain gage pressure transducers are used to measure __________ pressures.
A. gage as well as vacuum
B. absolute as well as differential
C. both (a) and (b)
D. neither (a) nor (b)
Question 330
The offset introduced by proportional controller with gain Kc in response of first order system can be reduced by
A. Reducing value of Kc
B. Introducing integral control
C. Introducing derivative control
D. None of the above
Question 331
Which of the following is a 'contact' pyrometer?
A. Resistance pyrometer
B. Optical pyrometer
C. Radiation pyrometer
D. Infra red pyrometer
Question 332
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
Question 333
Turbine flow meters are suitable for
A. Very limited flow ranges
B. Cryogenic flow measurements
C. Aerospace and in air borne applications
D. Both B and C
Question 334
Which of the following fluid flow measuring devices can measure the largest flow rate?
A. V-notch
B. Rotameter
C. Orificemeter
D. Weir
Question 335
Which of the following thermocouples can measure the maximum temperature?
A. Platinum-rhodium
B. Tungsten-molybdenum
C. Chromel-alumel
D. Iron-constantan
Question 336
Change of angle of refraction with composition comprises the working principle of a
A. Polarimeter
B. Polarograph
C. Spectrometer
D. Refractrometer
Question 337
Which of the following relates the emf. generated in a single homogeneous wire to the temperature difference?
A. Peltier effect
B. Thomson effect
C. Seebeck effect
D. None of these
Question 338
Which of the following thermocouples is capable of measuring a temperature of -50°C?
A. Platinum - platinum + rhodium
B. Chromel - alumel
C. Iron-constantan
D. Copper - constantan
Question 339
Stability of a control system containing a transportation lag can be best analysed by
A. Routh test
B. Root locus methods
C. Frequency response methods
D. None of these
Question 340
Resistance of a gas in a vessel is given by (where, P = pressure, V = volume of the vessel, n = no. of moles of the gas, R = gas constant)
A. V/nRT
B. nRT/V
C. nRT/P
D. p/nRT
Question 341
Routh test
A. Criterion provides information about the actual location of roots
B. Cannot be used to test the stability of a control system containing transportation lag
C. Criterion is not applicable to systems with polynomial characteristic equation
D. Can not determine as to how many roots of the characteristics equation have positive real roots
Question 342
Platinum resistance thermometer can be used upto antimony point which is __________ °C, and is the temperature of equilibrium between solid antimony & liquid antimony at normal atmospheric pressure.
A. 961.93
B. 630.74
C. 1064.43
D. 1261.93
Question 343
pH meter has
A. One cell
B. Two cells
C. Three cells
D. No cell
Question 344
A proportional controller with a gain of Kc is used to control a first order process. The offset will increase, if
A. Kc is reduced
B. Kc is increased
C. Integral control action is introduced
D. Derivative control action is introduced
Question 345
Which of the following is not the triple point of water?
A. 32°R
B. 273°K
C. 492°R
D. 32°F