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BSNL TTA Question 

Instruments and Measurement

Specialization 2007

Q.1.Instrument is a device for determining

• the magnitude of a quantity
• the physics of a variable
• either of the above
• both (a) and (b)

Q.2.Electronic instruments are preferred because they have

• no indicating part
• low resistance in parallel circuit
• very fast response
• high resistance in series circuit
• no passive elements.

Q.3.A DC watt meter essentially consist of

• two ammeters
• two voltmeters
• a voltmeter and an ammeter
• a current and potential transformer

Q.4.Decibel is a unit of

• power
• impedance
• frequency
• power ratio

Q.5.A dc voltmeter may be used directly to measure

• frequency
• polarity
• power factor
• power

Q.6.An accurate voltmeter must have an internal impedance of

• very low value
• low value
• medium value
• very high value

Q.7.The insulation resistance of a transformer winding can be easily measured with

• Wheatstone bridge
• megger
• Kelvin bridge
• voltmeter

Q.8.A 100 V voltmeter has full-scale accuracy of 5%. At its reading of 50 V it will give an error of

• 10%
• 5%
• 2.5%
• 1.25%

Q.9.You are required to check the p. f. of an electric load. No p.f. meter is available. You would use:

• a watt meter
• a ammeter, a voltmeter and a watt meter
• a voltmeter and a ammeter
• a kWh meter

Q.10.The resistance of a field coil may be correctly measured by using

• a voltmeter and an ammeter
• Schering bridge
• a Kelvin double bridge
• a Maxwell bridge

Q.11.An analog instrument has output

• Pulsating in nature
• Sinusoidal in nature
• Which is continuous function of time and bears a constant relation to its input
• Independent of the input quantity

Q.12.Basic charge measuring instrument is

• Duddel's oscillograph
• Cathode ray oscillograph
• Vibration Galvanometer
• Bailastic Galvanometer
• Battery Charging equipment

Q.13.A.C. voltage can be measured (using a d.c. instrument) as a value obtained

• by subtracting the d.c. reading from it's a.c. reading.
• Using the output function of the multimeter
• By using a suitable inductor in series with it
• By using a parallel capacitor with it
• None of the above

Q.14.A moving coil permanent magnet ammeter can be used to measure

• D. C. current only
• A. C. current only
• A. C. and D. C. currents
• voltage by incorporating a shunt resistance
• none of these

Q.15.Select the wrong statement

• the internal resistance of the voltmeter must be high
• the internal resistance of ammeter must be low
• the poor overload capacity is the main disadvantage of hot wires instrument
• the check continuity with multimeter, the highest range should be used.
• In moving iron voltmeter, frequency compensation is achieved by connecting a capacitor across its fixed coil.

Q.16.Which of the following instrument is suitable for measuring both a.c. and d.c. quantities.

• permanent magnet moving coil ammeter.
• Induction type ammeter.
• Quadrant electro-meter.
• Moving iron repulsion type ammeter.
• Moving iron attraction type voltmeter.

Q.17.Swamping resistance is used in moving coil instruments to reduce error due to

• thermal EMF
• temperature
• power taken by the instrument
• galvanometer sensitivity.

Q.18.A power factor meter is based on the principle of

• electrostatic instrument
• Electrodynamometer instrument
• Electro thermo type instrument
• Rectifier type instrument.

Q.19.A potentiometer recorder is used for

• AC singles
• DC signals
• both (a) and (b)
• time varying signals
• none of these.

Q.20.Transformers used in conjunction with measuring instruments for measuring purposes are called

• Measuring transformers
• transformer meters
• power transformers
• instrument transformers
• pulse transformers.

Q.21.Leakage flux in an electrical machine is measure by

• Ballistic galvanometer
• Flux meter
• Either (a) or (b)
• Vibration galvanometer
• CRO

Q.22.A C.R.O. is used to indicate

• supply waveform
• magnitude of the applied voltage
• B.H. loop
• all of these
• Magnitude of the current flowing in it.

Q.23.An oscillator is a

• an amplifier having feedback network
• a high gain amplifier
• a wide band amplifier
• a untuned amplifier
• None of these

Q.24.Distortion can be measured by

• Wave meter
• Digital filters
• Wein bridge circuit
• Bridge T filter circuit

Q.25.Series connected Q- meter is preferable for measurement of components having

• high impedance
• low impedance
• both (a) and (b)
• high frequency
• low capacitance

Q.26.A potentiometer is

• an active transducer
• a passive transducer
• a secondary transducer
• a digital transducer
• a current sensing transducer

Q.27.The basic components of a digital voltmeter are:

• A/D converter and a counter
• A/D converted and a rectifier
• D/A converter and a counter
• Ramp generator and counter
• Comparator

Q.28.Which of the following electrical equipment cannot convert ac into dc

• diode
• converter
• transformer
• mercury arc rectifier

Q.29.Voltage measurement are often taken by using either a voltmeter or

• an ammeter
• an ohmmeter
• an oscillator
• a watt-meter

Q.30.The electric device which blocks DC but allows AC is called:

• capacitance
• inductor
• an oscilloscope
• a watt-meter

Q.31.The range of an ammeter can be extended by using a

• shunt in series
• shunt in parallel
• multiplier in series
• multiplier in parallel

Q.32.A device that changes one form of energy to another is called

• rheostat
• oscillator
• transducer
• varicap

Q.33.Aquadag is used in CRO to collect

• primary electron
• secondary electron
• both primary and secondary
• none of above

Q.34.A vertical amplifier for CRO can be designed for

• only a high gain
• only a broad bandwidth
• a constant gain time bandwidth product
• all of the above

Q.35.One of the following is active transducer

• Strain gauge
• Selsyn
• Photovoltic cell
• Photo emissive cell

Q.36.The dynamic characteristics of capacitive transducer are similar to those of

• low pass filter
• high pass filter
• band pass filter
• band stop filter

Q.37.Thermocouples are

• passive transducers
• active transducers
• both active and passive transducers
• output transducers

Q.38.The size of air cored transducers as compare to iron core counter part are

• bigger
• smaller
• same
• None of these

Q.39.From the point of view of safety, the resistance of earthing electrode should be:

• low
• high
• medium
• the value of resistance of electrode does not effect the safety

Q.40.In CRT the focusing anode is located

• between pre accelerating and accelerating anodes
• after accelerating anodes
• before pre accelerating anodes
• none of above

Q.41.Which transducer converts heat energy into electrical energy

• I.V.D.T.
• thermocouple
• photo-conductor
• none of the above

Q.42.Which of photoelectric transducer is used for production of electric energy by converting solar energy

• photo emission cell
• photo diode
• photo transistor
• both (b) and (c)

Q.43.Which of the following instruments consumes maximum power during measurement?

• induction instruments
• hot wire instruments
• thermocouple instruments
• electro dynamometer instruments

Q.44.Which of the following meters has the best accurancy

• moving iron meter
• moving coil meter
• rectifier type meter
• thermocouple meter

Q.45.The function of the safety resistor in ohm meter is to

• limit the current in the coil
• increase the voltage drop across the coil
• increase the current in the coil
• protect the battery

Q.46.Which of the following instruments is free from hysteresis and eddy current losses?

• M.l. instrument
• electrostatic instrument
• electrodynamometer type instrument
• all of these

Q.47.The dielectric loss of a capacitance can be measured by

• Wien bridge
• Owen bridge
• Schering bridge
• Maxwell bridge

Q.48.Reed frequency meter is essentially a

• recording system
• deflection measuring system
• vibration measuring system
• oscillatory measuring system

Q.49.In measurements made using a Q meter,high impedance elements should preferably be connected in

• star
• delta
• series
• parallel

Q.50.A digital voltmeter measures

• peak value
• peak-to-peak value
• RMS value
• average value

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ELECTRICAL/ ELECTRONICS ENGINEERING 

Model Exam Paper

For Various Competitive Examinations

Q.1.The main scale of a vernier calliper is ruled in 1 mm units.The vernier scale is 49 mm long and divided in 50 units. The resolution of the vernier calliper is

• 0.002 mm
• 0.005 mm
• 0.01 mm
• 0.02 mm

Q.2.A frequency counter with a gating time of 50 ms counts 1254 cycles of an input square wave. The frequency of the input wave is

• 39.87 Hz
• 62.70 Hz
• 1.254 kHz
• 25.08 kHz

Q.3.A data acquisition system with the input range of ± 5.0 V has a 12-bit ADC in it.The resolution of the system is approximately

• 0.24 mV
• 0.48 mV
• 1.22 mV
• 2.44 mV

Q.4.Watt meters are based on the principle of

• permanent magnet moving coil meter
• electrodynamic meter
• electrostatic meter
• moving iron meter

Q.5.The resolution of a Gray-coded optical shaft encoder with 10-bit output is approximately

• 0.098°
• 0.176°
• 0.225°
• 0.352°

Q.6.The unit of the permittivity of free space (E0) is

• C2 N–1 m–2
• C2 N m2
• C–2 N m2
• C–2 N m–1

Q.7.A positively charged object is placed in the center of a room with a uniform magnetic field. If the magnetic field is pointing east, the object will

• move east
• move north
• move south
• remain stationary

Q.8.The input impedance of a quarter-wave long short-circuited lossless transmission line is

• purely reactive
• purely resistive
• infinite
• dependent on the characteristic impedance of the line

Q.9.For a plane wave propagating in the free space,

• the electric and magnetic fields are in parallel to the direction of propagation there is no field in the direction of propagation
• the electric and magnetic fields are out of phase
• the magnetic field amplitude is inversely proportional to the electric field amplitude
• None of these

Q.10.Which of the following materials has the largest energy gap between the conduction band and the valence band?

• Gold
• Silicon
• Doped germanium
• Porcelain

Q.11.The area of hysteresis loop in a ferromagnetic material is a measure of

• loss of energy
• loss of magnetic domain
• loss of magnetic dipole
• loss of eddy currents

Q.12.If a tetra- valent impurity is added to a pure silicon crystal at room temperature, it becomes

• a p-type semiconductor
• an n-type semiconductor
• an npn-type semiconductor.
• an insulator

Q.13.Unregulated dc power supply is not in need of

• Diode
• Transformer,
• Zener diode
• filter

Q.14.The eigen values of a skew-symmetric matrix are

• always zero
• always pure imaginary
• either zero or pure imaginary
• always real

Q.15.At room temperature, a possible value for the mobility of electrons in the inversion layer of a silicon n-channel MOSFET is

• 450 cm2/V-s
• 1350 cm2/V-s
• 1800 cm2/V-s
• 3600 cm2/V-s

Q.16.For parallel RLC circuit, which one of the following statements is NOT correct?

• The bandwidth of the circuit deceases if R is increased
• The bandwidth of the circuit remains same if L is increased
• At resonance, input impedance is a real quantity
• At resonance, the magnitude of input impedance attains its minimum value.

Q.17.Q-meter works on the principle of

• series resonance
• parallel resonance
• mutual inductance
• self inductance

Q.18.Which one of the following is a ceramic insulator?

• Mica
• Porcelain
• Liquid crystal
• Synthetic fiber

Q.19.Which one of the following represents a direct band-gap material?

• Si
• Ge
• GaP
• GaAs

Q.20.Which one of the following statements is NOT true?

• Rochelle salt exhibits ferroelectric property.
• Spontaneous polarization is a characteristic property of ferroelectric material.
• Spontaneous polarization of ferroelectric materials usually vanishes below ferroelectric Curie temperature.
• Ferroelectric materials exhibit hysteresis effect.

Q.21.Which one of the following diodes contains a metal-semiconductor junction?

• Tunnel diode
• Zener diode
• Schottky diode
• Gunn diode

Q.22.The most appropriate value (in Ohm) of the radiation resistance of a quarter wave monopole antenna is

• 36.5
• 50
• 73
• 120

Q.23.Which one of the following is an active transducer?

• Photo-voltaic cell
• Strain gauge
• Photo-emissive cell
• Synchro 

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