Showing posts with label Measurements and Instrumentation. Show all posts
Showing posts with label Measurements and Instrumentation. Show all posts

Saturday, 30 April 2016

Measurements Instrumentation Objective Type Questions Answers: Part-10

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Measurements Instrumentation Objective Type Questions Answers: Part-10

[1] A 12 bit counter type A/D converter uses a 1 MHz clock. Its maximum conversion time is
A) 1 �s
B) 12�s
C) 4096�s
D) 4�s


[2] A 12 bit counter type A/D converter uses a 1 MHz clock. Its maximum conversion rate is
A) 106 conversions/sec
B) 244 conversions/sec
C) 488 conversions/sec
D) 83 kilo conversions/sec


[3] An 8 bit converter type A/D converter makes at least 8000conversions/sec. The clock frequency used is
A) 2MHz
B)  8MHz
C)  1MHz
D)  4MHz


[4] The conversion time of a 12 bit successive approximation A/D converter using a 1 MHz clock is 
A) 1 �s
B) 12�s
C) 4096�s
D) 4095�s


[5] The resolution of a 12 bit D/A converter using a binary ladder is 
A) 4096
B) 0.02%
C) 2.4%
D) 4%


[6] A 12 bit counter type A/D converter uses a 1 MHz clock. If the full scale output is +10V, its resolution output is
A) 2.44mV
B) 2.4mV
C) 0.02V
D) 0.02mV


[7] A 10 bit resistive divider is constructed such that the current through the LSB resistor is 100�A. The maximum current that will flow through the MSB resistor is  
A) 200�A.
B) 1mA
C) 51.2mA 
D) 102.4mA


[8] For a certain 4 bit successive approximation A/D converter, the maximum ladder output is +8V. if a constant +6V is applied to the analog input the sequence of binary states for the SA register is 
A) 1111
B) 1010
C) 0110
D) 1011


[9] In the case of power measurement by two wattmeter method in a balanced 3F system with a pure inductive load 
A) both the  Wattmeter will indicate the same but of opposite sign.
B) both the Wattmeters will indicate zero.
C) both the Wattmeters will indicate same value and of the same sign.
D) one Wattmeter will indicate zero and the other non-zero value.


[10] The sensitivity of an instrument is 
A) smallest increment in the output the can be detected with certainity.
B) largest input change to which the instrument fails to respond.
C) ratio of the change in the magnitude of the output to the corresponding change in the magnitude of the input.
D) closeness of the output values for repeated applications of a constant input.

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Saturday, 27 December 2014

Measurements and Instrumentation Objective Questions with Answers: Part-9

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MEASUREMENTS AND INSTRUMENTATION OBJECTIVE QUESTIONS WITH ANSWERS
[1] A rectifier type instrument is connected to 100VDC and is operated in the DC measuring module reads
(a) 111V
(b) 90V
(c) 50V
(d) 100V


[2] A permanent magnet moving coil ammeter has a coil resistance of 99ohm and Full Scale Deflection(FSD) current of 0.1mA. Shunt resistance is 1 ohm. Current through the meter at 0.5 F.S.D is
(a) 0.007mA
(b) 0.05mA
(c) 0.023mA
(d) 0.1mA


[3] One single phase wattmeter operating on 230V and 5A for 5 hours makes 1940 revolutions. Meter constant in revolutions is 400. What is the power factor of the land?
(a) 1
(b) 0.84
(c) 0.73
(d) 0.65


[4] For power measurement of three phase circuit by two wattmeter method, when the value of power factor is less than 0.5 lagging
(a) one of the wattmeters will read zero
(b) both give the same readings
(c) one of the wattmeter connections will have to be reversed
(d) pressure coil of the wattmeter will become ineffective.


[5] When using ohmmeter, applied voltage is to be disconnected from the circuit because
(a) Voltage source will increase resistance
(b) Current will decrease resistance
(c) the ohmmeter has its own internal battery
(d) non of the above


[6] Which wave has the least form factor?
(a) Square wave
(b) Rectangular wave
(c) Sine wave
(d) Triangular wave


[7] With a sweep time 10ms across the screen the approx. horizontal sawtooth frequency will be
(a) 50Hz
(b) 100Hz
(c) 1kHz
(d) 500Hz


[8] A spring controlled indicating instrument has a deflection of 90deg for maximum current I. The corresponding deflection for a gravity controlled instrument is
(a) 90�
(b) 120�
(c) 30�
(d) 0�


[9] It is found that 10A current passes through a resistor of 10ohms. The resistor has 5% tolerance . The error in measurement of current can be as high as 5%. What is max error in measurement of power, calculated from measured value of I and the nominal value of resistor?
(a) 100 W
(b) 150W
(c)50W
(d) 200W


[10] A resistor of 10Kohms with 5% tolerance is connected in parallel with a 5Kohms resistor of 10% tolerance. What is the tolerance limit for the parallel network?
(a) 5%
(b) 6.67%
(c) 10%
(d) 8.33%


[11] The resistance offered to the passage of an in-varying current by a column of mercury at the temperature of melting ice of mass 14.4521 gms of uniform cross-sectional area and length 106.3cm is
(a) Standard ohm
(b) One international ohm
(c) One ohm according to SI units
(d) One ohm according to working standards
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Tuesday, 18 November 2014

Measurements Instruments Objective Questions with Answers: part-8

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Measurements and Instruments Objective Questions with Answers

[1] The most preferred material for the control spring is
(a) German silver
(b) Platinum silver
(c) Silicon bronze
(d) Phosphor bronze


[2] A moving coil instrument is used as an ohmmeter. The indicating scale of the meter will be
(a) Hyperbolic
(b) Logarithmic
(c) Linear
(d) Inverse linear


[3] For high accuracy the meter has
(a) Supporting mirror
(b) Hand drawn scale
(c) Printed scale
(d) Scale with sharp pointer


[4] Among the voltages to various electrodes in a CRT the voltage is the highest on
(a) Aquadag
(b) Focusing anode
(c) Deflection plates
(d) PD anode


[5] In a free running oscilloscope the horizontal deflection system is driven by a ........ waveform
(a) Step
(b) Impulse
(c) Ramp
(d) DC


[6] A Lissajous patterns are used to measure
(a) Voltage and frequency
(b) Frequency and Phase shift
(c)  Frequency and amplitude distortion
(d) Amplitude and flux


[7] The shunt used in milliammeter
(a) will extend the range and reduce the meter resistance
(b) will extend the range and increase the meter resistance
(c) will decrease the range and meter resistance
(d) will not affect the meter


[8] The electrostatic instruments can be used without serious loss of accuracy upto ......... frequency
(a) 100Hz
(b) 100kHz
(c) 1 MHz
(d) 10MHz


[9] In the case of PMMC rectifier type instruments, the deflecting torque is proportional to
(a) Average value of AC current
(b) RMS of AC
(c) Instantaneous value
(d) Peak value


[10] Inductance and capacitance in the electrostatic system of units has the dimensions of
(a) mass
(b) mass-time
(c) mass length/time
(d) length


[11] For the indicating instrument the preferred damping condition is
(a) Critically damped
(b) a damping coefficient of 0.8 to 1
(c) Overdamped
(d) Underdamped


[12] One international ohm is equal to
(a) 1.00049 absolute ohm
(b) 0.99951 absolute ohm
(c) 0.969 absolute ohm
(d) 1.049 absolute ohm



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Sunday, 19 October 2014

Measurements Instrumentation Objective Questions Answers: Part-7

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Measurements Instrumentation Objective Questions with Answers

[1] A mulliammeter can be used as
(a) Voltmeter and ammeter
(b) Wattmeter
(c) Ohmmeter
(d) Frequency meter


[2] Which instrument has identical calibration for ac as well as dc values?
(a) Hot wire type
(b) Moving coil type
(c) Induction type
(d) Moving iron type


[3] An instrument to be used for measurement and control should preferably have
(a) Dead zone and dead time
(b) Linear output and fast response
(c) Non-linear output
(d) A highly damped response


[4] The current coil of a wattmeter is connected to the CT of R-phase. The potential coil is connected across Y and B phases. The wattmeter measures
(a) Active power in R phase
(b) Active power of Y phase
(c) Reactive power of R phase
(d) Power proportional to 3 phase power if the load is balanced


[5] The problem of Electro-static coupling in a transformer is acute at
(a) Low frequencies
(b) Power frequencies
(c) High frequencies
(d) High load on the transformer


[6] Which meter is suitable for the measurement of 10mV at 50MHz?
(a) Moving iron voltmeter
(b) VTVM
(c) Moving coil voltmeter
(d) CRO


[7] It can be stated that
(a) CT operates at almost the same flux density as a PT
(b) CT operates with a higher flux density than PT
(c) CT operates with considerably lower flux density than a PT
(d) no generalisation can be made with regard to the flux densities in CT and PT


[8] The thermocouple instruments do not have
(a) High sensitivity
(b) Absence of frequency error
(c) Independence of ambient temperature
(d) High degree of measuring accuracy


[9] Some wire- wound resistors have bifilar winding. This type of winding is used to
(a) Increase the thermal stability
(b) Reduce the tolerance
(c) Reduce the inductance of winding
(d) Double the power rating of the resistor


[10] Wien bridge is useful for measuring
(a) Very high frequency
(b) Low frequency
(c) Medium frequency
(d) High frequency


[11] A megger is usually
(a) Moving iron type instrument
(b) Electro-static type instrument
(c) Hot-wire type instrument
(d) Moving coil type instrument


[12] A moving iron ammeter may be compensated for frequency errors by
(a) a shunt resistance
(b) a series inductance
(c) shunt capacitance
(d) series resistance


[13] Ryall crest voltmeter is used for measurement of
(a) AC voltage of any form
(b) Low frequency voltage
(c) High DC voltage
(d) High AC voltage


[14] Jewels are used in instruments for the purpose of
(a) Damping
(b) Torque control
(c) Suppressing noise
(d) Bearing


[15] The thermocouple instrument will measure
(a) Current
(b) Voltage
(c) Flux
(d) None of the above
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Wednesday, 27 August 2014

Measurements Instrumentation Objective Questions Answers: Part-6

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MCQ in Electrical Measurements and Instrumentation

[1] A 10MHz CRO has
(a) 5MHz sweep
(b) 10MHz vertical oscillator
(c) 10MHz horizontal oscillator
(d) 10MHz supply frequency


[2] Which of the following instruments can be used to measure AC current only?
(a) Permanent Magnet Type ammeter
(b) Induction type ammeter
(c) Moving iron voltmeter
(d) Moving iron ammeter
Answers:
1. D only
2. B only
3. A, B, D
4. B and D only


[3] An oscilloscope indicates
(a) Peak to peak value of voltage
(b) DC value of voltage
(c) RMS value
(d) Average value


[4] In a ballistic galvanometer, the deflecting torque is proportional to
(a) the current through coil
(b) square of current through coil
(c) square-root of current through coil
(d) sine of measured


[5] The error of an instrument is normally given as a percentage of
(a) measured value
(b) full-scale value
(c) mean value
(d) rms value


[6] If the instrument is to have a wide range, the instrument should have
(a) Linear scale
(b) Square-law scale
(c) Exponential scale
(d) Logarithmic scale


[7] The resistance can be measured most accurately by
(a) Voltmeter-ammeter method
(b) bridge method
(c) multimeter
(d) Megger


[8] The repeat accuracy of an instrument can be judged from its
(a) static error
(b) linearity error
(c) dynamic error
(d) standard deviation of error


[9] Which of the following meters has a linear scale?
(a) Thermocouple meter
(b) Moving iron meter
(c) Hot wore meter
(d) Moving coil meter


[10] No eddy current and hysteresis losses occur in
(a) Electrostatic instruments
(b) PMMC instruments
(c) Moving iron instruments
(d) Electrodynamo meter instruments


[11] Two voltmeters have the same range 0-400V. The internal impedance are 30,000 Ohms and 20,000 Ohms. If they are connected in series and 600V be applied across them, the readings are
(a) 360V and 240V
(b) 300V each
(c) 400V and 200V
(d) one of the meters out of the range and other 100V


[12] The full-scale deflection current of an ammeter is 1 mA and its internal resistance is 100Ohm. If this meter is to have full deflection at 5A, what is the value of the shunt resistance to be used?
(a) 49.99 Ohms
(b) 1/49.99 ohms
(c) 1 Ohm
(d) 2 Ohms


[13] The full-scale deflection current of an ammeter is 1 mA and its internal resistance is 100Ohm. This is to have full deflection when 100V is measured. What is the value of series resistor to be used?
(a) 99.99 K ohms
(b) 100 K ohms
(c) 99.99 ohms
(d) 100 ohms


[14] Why is a MISC meter not recommended for DC measurement?
(a) The meter is calibrated for AC and it's error for DC would be high
(b) The meter does not respond to DC signals
(c) The error is high due to hysteresis effect
(d) The error is high due to eddy current effect


[15] The EMF of Weston standard cell is measured using
(a) Moving- iron meter
(b) Moving-coil meter
(c) Digital Volt meter
(d) Potentiometer


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Thursday, 7 August 2014

Measurements Instrumentation Objective Questions Answers: Part-5

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Objective Questions from Measurements Instrumentation 

[1] A CRO can display
(a) AC signals
(b) DC signals
(c) Both AC and DC signals
(d) Time invariant signals


[2] The internal resistance of an ammeter should be
(a) Very small
(b) medium
(c) High
(d) Infinity


[3] A galvanometer has
(a) air friction damping
(b) fluid friction damping
(c) Spring coil damping
(d) Eddy current damping


[4] Electrostatic instruments are normally used for
(a) Low current measurements
(b) High current measurements
(c) Low voltage measurements
(d) High voltage measurements


[5] In a moving coil instrument, the deflecting torque is proportional to
(a) Current
(b) Square of the current
(c) Squareroot of the current
(d)  sine of the measurand


[6] The absolute measurement of resistance is done by
(a) Ohm's law method
(b) Bridge Method
(c) Rayleigh method
(d) Lorenz method


[7] To measure the flux, devices used are based on
(a) Voltaic effect
(b) Piezo-electric effect
(c) Hall effect
(d) Photo-voltaic effect


[8] The form factor in AC is the ratio of
(a) peak value to average value
(b) peak value to rms value
(c) rms value to average value
(d) rms value to peak value


[9] PMMC type instruments normally use
(a) Air friction damping
(b) Fluid friction damping
(c) Eddy current damping
(d) None of the above


[10] In a moving iron meter, the deflecting torque is proportional to
(a) Current through the coil
(b) Square of the current through the coil
(c) Sine of the measurand
(d) Squareroot of the measurand


[11] In a gravity controlled instrument, the deflection angle is proportional
(a) Measurand
(b) Square of the measurand
(c) sine inverse of measurand
(d) sine of the measurand


[12] Ampere is one of the
(a) Supplementary units
(b) Derived units
(c) Base units
(d) Units used to measure charge


[13] Direct method is used to measure
(a) Length
(b) Temperature
(c) Pressure
(d) Voltage



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Monday, 4 February 2013

Measurements Instrumentation Objective Questions: Part-4

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[1] A hot-wire ammeter
A. Can measure ac as well as dc
B. Registers current changes very fast
C. Can indicate very low voltages
D. Measures electrical energy


[2] The device used to indicate the presence of an electric current is
A. Electrometer
B. Galvanometer
C. Voltmeter
D. Coulometer


[3] A watt-hour meter measures
A. Voltage
B. Current
C. Energy
D. Power


[4] A voltmeter should have
A. Low internal resistance
B. High internal resistance
C. Electrostatic plates
D. A sensitive amplifier


[5] An average-reading digital multimeter reads 10V when fed with a triangular wave, symmetric about the time-axis.For the same input an rms-reading meter will read  [GATE]
A. 20/v3
B. 10/v3
C. 20v3
D. 10v3

[6] The figure shows a three-phase delta connected load supplied from a 400V,50Hz,3-phase balanced source. The pressure coil(PC) and current coil(CC) of a wattmeter are connected to the load as shown,with the coil polarities suitably selected to ensure a positive deflection. The wattmeter reading will be   [GATE]
A. 0
B. 1600Watt
C. 800Watt
D. 400Watt

[7] The probes of a non-isolated, two channel oscilloscope are clipped to points A,B and C in the circuit of the adjacent figure. Vin is a square wave of a suitable low frequency. The display on Ch1 and Ch2 are as shown on the right. Then the "signal" and "ground" probes S1, G1 and S2, G2 of Ch1 and Ch2 respectively are connected to points [GATE 2007]

A.  A, B, C, A
B.  A, B, C, B
C.  C, B, A, B
D.  B, A, B, C


[8] An analog voltmeter uses external multiplier settings. With a multiplier setting of 20kO, it reads 440V and-with a multiplier setting of 80kO it reads 352V. For a multiplier setting of 40kO,voltmeter reads  [GATE2012]
A. 371V
B. 383V
C. 394V
D. 406V


[9] The rate at which charge carriers flow is measured in
A. Coulombs
B. Amperes
C. Watt-hour
D. Watts


[10] The main problem with bar-graph meters is that
A. They are not very sensitive
B. They are unstable
C. They cannot give very precise readings
D. They can display only peak values


[11] A dynamometer type wattmeter responds to the [Gate 1997]
(a) Average value of the active power
(b) Average value of reactive power
(c) Peak value of the active power
(d) Peak value of the reactive power


[12] A transfer instrument employed in the standardization of a polar type ac potentiometer is [Gate 1997]
(a) An electrostatic instrument
(b) A thermal instrument
(c) A dynamometer instrument
(d) A moving coil instrument


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Friday, 9 November 2012

Measurements Competitive Objective Questions

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Competitive Exams Objective Questions from Measurements:

[1] Consider the following statements:
1. The main shortcomings of diaphragms are that they are prone to shock vibrations.
2. Diaphragms have the advantages of high accuracy and good dynamic response
3. Selection of material for diaphragms mainly depends upon temperature range and chemical nature of fluid coming in contact with diaphragm during pressure measurement.
Which of the above statements is/are correct?   [IES2010]
A.  1,2 and3
B.  2 and 3 only
C.  1 only
D.  1 and 2 only


[2] If reflection coefficient for voltage be 0.6, the voltage standing wave ratio(VSWR) is   [IES2010]
A.0.66
B.4
C.1.5
D.2


[3] A resistance strain gage with gage factor (Sf) of 2 is bonded to a steel member,which is subjected to a strain of 1 x 10-6.The original resistance value of this strain gage is 120O.The change in resistance due to the applied strain is   [IES2010]
A. 60O
B. 240 x 10-6 O
C. 240O
D. 60 x 10-6 O


[4] Consider the following statements:   [IES2010]
Piezoelectric materials
1. Crystal can be shown as electrical equivalent circuit similar to an inductor and a capacitor(Tank circuit).
2. Quartz,Rochelle salt,tourmaline.
3. Used in voltage stabilizers.
4. This exhibits the reverse effect of electrostriction.
Which of the above statements are correct?
A. 1,2 and 4 only
B. 1 and 2 only
C. 2 and 4 only
D. 1,2,3 and 4


[5] Consider the following units for the measurement of pressure directly: [IES2010]
1. Rolta meter
2. Bourdon tube
3. Planti meter
4. Vanes
Of these, the pressure can be measured by
A. 1 and 2 only
B. 3 and 4 only
C. 2 only
D. 1,2,3 and 4

[6] The measurement of Hall coefficient of a semiconductor with one type of charge carrier gives the information about [IES2010]
A. Sign of charge carrier
B. Density of charge carrier
C. Both sign and density of charge carrier
D. Mass of the charge carrier

 
[7] A piezoelectric crystal has a thickness of 2.5mm and a voltage sensitivity of 0.05Vm/N. The piezoelectric crystal is subjected to an external pressure of 1.6 x 106N/m2,then the corresponding output voltage is, [IES2010]
A. 200V
B. 3.2 x 109V/m of thickness
C. 0.07 x  10-9V/(m3/New)
D. 200m V


[8]The two inputs of a CRO are fed with two stationary periodic signals. In the X-Y mode, the screen shows a figure which changes from ellipse to circle and back to ellipse with its major axis changing orientation slowly and repeatedly. The following inference can be made from this. [GATE2009]
A. The signals are not sinusoidal
B. The amplitudes of the signals are very close but not equal
C. The signals are sinusoidal with their frequencies very close but not equal
D. There is a constant but small phase difference between the signals

[9]The pressure coil of a dynamo meter type wattmeter is [GATE2009]
A. Highly inductive
B. Highly resistive
C. Purely resistive
D. Purely inductive

[10]The measurement system shown in the figure uses three sub systems in cascade whose gains are specified as G1, G2 and 1/G3. The relative small errors associated with each respective subsystem G1, G2,G3 are e1,e2 and e3.The error associated with the output is [GATE2009]
A. e1+e2+1/e3
B. (e1.e2)e3
C. e1+e2-e3
D. e1+e2+e3

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