JNTU
JNTU B.Tech IV ELECTRONIC MEASURING INSTRUMENTS Previous Question Paper (July - 2021 - R16)
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The expected value of current through a resistor is 1330mA, but the measurement yields a current value of 1286mA. Calculate the percentage of accuracy and percentage of error.
Answer
Given the expected (true) value At = 1330 mA and the measured value Am = 1286 mA, the absolute error e is calculated as:
The percentage of error is calculated as:
The percentage of accuracy is defined as:
List out the characteristics of instruments that are used to measure an unvarying process condition.
Answer
When measuring an unvarying (static) process condition, the performance of an instrument is defined by its static characteristics. The key characteristics include:
- Accuracy: The closeness with which an instrument reading approaches the true value of the quantity being measured.
- Precision: The measure of the reproducibility of the measurements, indicating how closely a set of readings for the same input agree with each other.
- Sensitivity: The ratio of the change in output of the instrument to the change in the input or measured quantity.
- Resolution: The smallest change in the input value that produces a detectable change in the instrument output.
- Linearity: The ability of the instrument to produce an output that is directly proportional to the input over the operating range.
- Hysteresis: The difference in output reading for the same input when approached from increasing versus decreasing directions.
- Threshold: The minimum input value required to produce a detectable change in the output.
- Drift: The variation in the output reading over a period of time while the input remains constant, often caused by environmental changes.
- Dead Zone: The range of input values for which the instrument produces no output response.
An engineer wants to generate a sawtooth wave that varies in frequency from a fraction of Hertz to several hundred KiloHertz. With a neat block diagram design the device and explain its working.
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Draw the block diagram that provides a sinusoidal output voltage whose frequency varies continuously over audio frequency band.
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Explain how an unknown resistance can be measured when it is connected in series to the D’Arsonval moment.
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A CRO is set to a time base of 0.1 ms/cm with a 10cm amplitude. Sketch the display of the pulse signal waveform with a pulse repetition rate of 3000Hz and duty cycle of 30%.
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An engineer wants to plot the instantaneous relation between two variables G = F(s). Explain how plotting of one variable against another variable is done.
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Explain the working of Servo transducer and what are the applications of it?
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Briefly explain the working principles and measurement of force by any two nonelectric techniques?
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Describe the method of measuring flow rate with a neat diagram.
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The accuracy of five digital voltmeters are checked by using each of them to measure a standard 2.0000V from a calibration instrument. The voltmeter readings are as follows: V1=2.001v, V2=2.002v, V3=1.999v, V4=1.998v and V5=2.0000v. Calculate the average measured voltage and the average deviation.
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What is the difference between pulse generator and square wave generator? Also discuss requirements of Pulse.
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Design a multirange ammeter with ranges of 0-100 mA, 0-300 mA, 0-600 mA, 0-2 A employing individual shunts for each range. A D' Arsonval movement with an internal resistance of 600 Ω and a full scale current of 200 μA is available.
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Draw the basic block diagram of an oscilloscope and explain the function of each block.
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Sketch the DC signal conditioning circuit for pressure measurement using strain gauge. Justify it.
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An ac LVDT has the following data: Input = 8.2 V, Output = 4.3 V, range ± 0.3 in. Determine (i) Calculate the output voltage Vs Core position for a core moment going from + 0.45 in. to – 0.30 in. (ii) The output voltage when the core is -0.25 in. from the centre.
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