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ইলেকট্রিক্যাল মেজারমেন্ট ইন্ড মেজেরিং ইন্সট্রুমেন্ট MCQ
21. In a Weston synchronoscope, the fixed coils are connected across-
Bus-bars
A lamp
Incoming alternator
None of the above
ব্যাখ্যা: in a western synchronoscope, the fixed coils are connected across incoming alternator.
22. The operating voltage of a Meggar is about-
6V
12V
40V
100V
ব্যাখ্যা: আমাদের দেশে সাধারণতঃ 500V, 1000V, 2000V-এর মেগার পাওয়া যায়। টেস্ট ভোল্টেজ অনুযায়ী মেগার ইনসুলেশন 'টেস্টার' বিভিন্ন প্রকারের হয়ে থাকে। যথা- 100V, 250V, 500V, 1000V, 2500V, 10,000V.
23. Alternating current is measured by-
Induction ammeter
Permanent magnet type ammeter
Electrostatic ammeter
Moving iron repulsion type voltmeter
ব্যাখ্যা: Alternating current is measured by induction ammeter because the operation of induction type instruments depends on the production of torque due to the reaction between two magnetic fluses having some phase difference between the flux of an AC magnet and the eddy current induced by this flux.
24. The internal resistance of an ammeter should be-
Very small
High
Medium
Infinity
25. A dynamometer wattmeter can be used for-
DC only
AC only
Both DC and AC
Any of the above
26. In a moving coil instrument, the deflecting torque is proportional to-
Current
Square of the current
Squareroot of the current
Sine of the measurand
ব্যাখ্যা: একটি ইনস্ট্রুমেন্টের ডিফ্লেকটিং টর্ক (To), যে কারেন্ট (1) পরিমাণ করতে হবে তার সাথে সরাসরি সমানুপাতিক।
27. A moving iron instrument can be used for-
DC only
AC only
Both DC and AC
None of the above
ব্যাখ্যা: মুভিং আয়রন ইনস্ট্রমেন্ট এসি ও ডিসি উভয় সরবরাহে ব্যবহৃত হয়।
28. An instrument transformer is used to extend the range of-
Induction instrument
Electrostatic instrument
Moving coil instrument
Any of the above
29. In an energy meter braking torque is produced to--
Safeguard it against creep
Brake the instrument
Bring energy meter to stand still
Maintain steady speed and equal to driving torque
ব্যাখ্যা: In an energy meter, a barking torque is produced to maintain a steady speed and equal to driving torque. A permanent magnet positioned near the edge of the aluminum disc from the braking system.
30. In a dynamometer 3-phase power factor meter, the planes of the two moving coils are at----
0°
60°
90°
120°
ব্যাখ্যা: ডায়ানামোমিটার টাইপ পাওয়ার ফ্যাক্টর মিটারে দুটি প্রেসার কয়েলের প্ল্যানের মধ্যবর্তী কোণ 90° এবং 3- power factor meter প্রেসার সার্কিটদ্বয়ের মধ্যবর্তী কোণ 120°
31. Commonly used instruments in power system measurement are-
Induction
Rectifier
Moving coil or iron
Electrostatic
ব্যাখ্যা: Induction type instruments are commonly used in power system measurement. These types of instruments are used only for AC measurements.
32. The disc of an instrument using eddy current damping should be of-
Conducting and magnetic material
Non-conducting and magnetic material
Conducting and nonmagnetic material
None of the above
ব্যাখ্যা: Eddy current damping uses conducting and nonmagnetic material.
33. An oscilloscope indicates-
Peak to peak value of voltage
DC value of voltage
RMS value
Average value
ব্যাখ্যা: The automatic measurement of various parameters of the signal, like its frequency, peak-to-peak voltage, duty cycle and rise time.
34. Ampere is one of the-
Supplementary units
Derived units
Base units
Units used to measure charge
ব্যাখ্যা: Current unit is Ampere. Ampere is SI base unit.
35. The pointer of an indicating instrument should be--
Very light
Very heavy
Either (a) or (b)
Neither (a) nor (b)
ব্যাখ্যা: The pointer of an indicating instrument should be very light
36. Direct method is used to measure-
Length
Pressure
Temperature
Voltage
ব্যাখ্যা: Direct method is used to measure length.
37. Ryall crest voltmeter is used for measurement of--
AC voltage of any form
Low-frequency voltage
High-DC voltage
High-AC voltage
ব্যাখ্যা: High AC voltage measurement used Ryall crest voltmeter,
38. For measurement of inductance having high value, we should use-
Maxwell's bridge
Maxwell Wien bridge
Hay's bridge
Any of the above
ব্যাখ্যা: The Hay's bridge is used for determining the self- inductance of the circuit. The bridge is the advanced from of maxwell's bridge. The maxwell's bridge is only appropriate for measuring the medium quality factor. For measuring the high quality factor the Hay's bridge is used in the circuit
39. An ohmmeter is a---
Moving iron instrument
Moving coil instrument
Dynamometer instrument
None of the above
40. In order to achieve high accuracy, the slide wire of a potentiometer should be-
As long as possible
As short as possible
Neither too small nor too large
Very thick