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Note Book

Electrician Trade

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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

Ans: D

[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

Ans: A


 

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


Ans:B


 

[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


Ans: D


 

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


Ans: C


 

[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


Ans:B


 

[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


Ans: A


 

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


Ans:B


 

[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


Ans: A


 

[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


Ans: D


  

[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


Ans: B


 

[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


Ans: A


 

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

Ans:A

[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


Ans: A



[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


Ans:B

[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


Ans: C

[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


Ans: C

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


Ans:D

[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

Ans: C

[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


Ans: D

[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


Ans: C

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


Ans: D
 

[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
Ans: D
 
[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
Ans: C
 
[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
Ans:D
 
[14] Jewels are used in instruments for the purpose of
(a) Damping
(b) Torque control
(c) Suppressing noise
(d) Bearing
Ans: D
 
[15] The thermocouple instrument will measure
(a) Current
(b) Voltage
(c) Flux
(d) None of the above
Ans: D