JNTU
JNTU B.Tech III ELECTRONIC MEASUREMENTS AND INSTRUMENTATION Previous Question Paper (January / February - 2023 - R18)
Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
Part A
What are the types of errors in measuring instruments?
Answer
Errors in measuring instruments are generally categorized into three primary types:
- Gross Errors: These result from human mistakes in reading, recording, or using instruments, such as improper adjustment or misinterpretation of data.
- Systematic Errors: These are consistent, repeatable errors inherent to the measurement system, including instrumental errors (e.g., friction, hysteresis), environmental errors (e.g., temperature, pressure), and observational errors (e.g., parallax).
- Random Errors: These are unpredictable variations caused by unknown or fluctuating factors that remain after systematic and gross errors have been minimized.
Enumerate the static characteristics of an instruments.
Answer
The static characteristics of an instrument define its performance when measuring a constant input or an input that varies very slowly over time. The primary static characteristics are:
- Accuracy: The closeness with which an instrument reading approaches the true value of the quantity being measured.
- Precision: A measure of the reproducibility or consistency of the measurements, indicating the degree to which successive readings differ from each other.
- Sensitivity: The ratio of the change in output of the instrument to the change in the input quantity being measured.
- Resolution: The smallest change in the measured input that produces a detectable change in the instrument's output.
- Linearity: The ability of an instrument to produce an output that is directly proportional to the input over the specified range.
- Hysteresis: The difference in output readings for the same input when approached from increasing versus decreasing directions.
Mention the various types of signal analyzer.
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Briefly explain principle of working of frequency synthesizer.
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What is the purpose of time base generator in CRO?
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What are the types of CRO Probes?
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State the properties of piezoelectric transducers.
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Explain the basic principle used in syncros.
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Give the uses of D.C. bridges.
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Enumerate the different types of temperature measuring devices.
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Part B
A 100V moving iron voltmeter is intended for 50Hz, has a resistance of 3KΩ. Find the series resistance required to the extent of the range of the instrument to 200V. If the 200V instrument is used to measure a dc voltage of 150V. Find the voltage across the meter?
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With relevant diagram, explain the working of True RMS Responding Voltmeters.
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Explain about dynamic characteristics of measuring instrument.
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Briefly discuss the operation of DC Voltmeter with help of neat diagram.
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Describe the diagram with operation of a harmonic distortion analyser using Wein bridge and frequency selective type.
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With relevant diagram, explain the working of video signal generator
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Explain the working of a standard sweep generator with diagram.
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Discuss the principle of RF signal generator operation.
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Explain the major parts of CRT with a block diagram
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Discuss in detail, the construction and working of a digital sampling oscilloscope.
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Explain with the block diagram how the digital frequency can be measured using counter/meter instrument.
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Explain with a diagram how frequency and phase can be measured using a Lissajous method.
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Draw the diagram of Resistance Thermometer and explain its operation.
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Define piezoelectric effect. Write the applications of piezoelectric transducer.
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With a neat sketch, explain the operation of LVDT.
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With relevant diagram, explain the working of hot wire anemometer.
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In the Wheatstone bridge, the values of resistances of various arms are P= 1000 Ω, Q= 100 Ω, R= 2,005 Ω and S= 200 Ω. The battery bas an emf of 5 V and negligible internal resistance. The galvanometer bas a current sensitivity of 10 mm/μA and an internal resistance of 100 Ω. Calculate the deflection of the galvanometer and the sensitivity of the bridge in terms of deflection per unit change in resistance.
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With help of neat diagram, explain the working of any one type of humidity measuring instrument.
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Derive an equation to find the sensitivity of the wheat stone bridge.
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Explain the different type of pressure measuring devises with a relevant diagram.
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