Name of the University : Jadavpur University
Department : Power Engineering
Degree : B.E
Subject Name : Sensors & Transducers
Year/Sem : IV/I
Website : jaduniv.edu.in
Document Type : Model Question Paper
Download Model/Sample Question Paper : https://www.pdfquestion.in/uploads/dspace.jdvu.ac.in/6161-Sensors%20&%20Transducers.pdf
Jadavpur Sensors & Transducers Question Paper
Bachelor Of Power Engineering Examination, 2011 :
( 4th Year, 1st Semester )
Time : Three Hours
Full Marks – 100
Related : Jadavpur University Design High Pressure Boilers B.E Question Paper : www.pdfquestion.in/6160.html
Answer any Five :
1. a) Define linearity and sensitivity of a sensor.
b) A seosor has a characteristic defined by
calculate the cut-off frequency.
c) If the sensor is used to measure a periodic displacement with a frequency of 100 Hz. and an amplitude 1mm what should be the amplifier gain if the amplifier supply voltage is ±5 Volts.
d) What will happen if the frequency of the oscillations increase? 4+6+6+4
2. a) A disc is rotating at a certain rpm. If an 8 bit shaft encoder is used to sense position as well as speed, what is the resolution with which position can be sensed?
b) With what resolution can you sense the speed, assuming that the shaft is decoded using a laser stylus and the processing time is negligible.
c) If the disc rotates at 3600 rpm what is the maximum decoding and processing time if the nett angular displacement has to be detected with the resolution in 2a. 5+8+7
3. a) Derive an expression for sensitivity of a piezo-resistive crystal subjected to a strain.
b) Assuming appropriate resistance and capacitance deduce an expression for the output from the sensor subjected to time varying displacements.
c) What are the different configurations in which a piezoresistive sensor can be used? 7+7+6
4. a) With suitable assumptions design a circuit with LM-335 capable of measuring temperature in the range 0 to 100oC.
b) Derive an expression for level measurement in a cylindrical vessel filled with a non-conducting fluid using a capacitive transducer. 10+10
5. a) Explain the principle of temperature measurement using infra-red thermometry.
b) Deriving necessary expressions for measurement of temperature using a 3-wire Pt 100, design a bridge circuit for temperature measurement within a range DToC. 10+10
6. a) The emitted radiation from a piece of metal is measured and the temperature is found to be 1065oC. Assuming a surface emisivity of 0.82. It was later found out that the true emissivity is 0.85. Calculate the error in temperature measurement.
b) A thermocouple circuit uses chromel-alumel thermocouple which gives an emf of 33.3 mV when measuring a temperature of 800oC with a reference temperature of 0oC. The resistance of the meter coil R m is 50W and a current of 0.1mA gives a full scale deflection. The resistance of the junctions and leads together is 12W.
Calculate (i) the series resistance R to obtain a full scale deflection for a temperature of 800oC and (ii) temperature error due to a rise of 10o in the resistance R m assuming a=0.00426/oC. 10+10
7. a) Derive an expression for Doppler shift due to scattering using a Laser-Doppler velocimeter.
b) Represent the schematic using a suitable diagram and state the requirements for the detector. 15+5
8. a) With a suitable sketch derive an expression for fluid velocity measurement using an ultrasonic probe. 10
b) How is PH measured? 10
Principle Of Electrical Engineering
Units and dimensions of electrical and magnetic quantities, conversion between various ystem of units, analysis of DC electric circuits, Kirchoff’s laws, fundamental relations of electrostatic field – Coulomb’s law, Gauss’s law, electric flux, flux density and field density and field intensity, line charge, potential function, stored energy in electric field -capacitance calculation for simple geometries, elctro-magnetism,
Ampere’s law, magnetic flux, flux density and field intensity, magnetic force, Faraday’s law, inductance calculation for simple geometries. AC fundamentals – sinusoidal waves and their phasor representation, concept of impedance and admittance, analysis of R-L-C series andparallel circuits – resonance, Q-factor.
Concept of polyphase circuits – relation between 3-phase voltage, current and power in different passive circuits, analysis of balanced 3-phase circuits, 3-phase power measurement, single line diagram, relation between voltage, current and power unbalanced 3-phase circuits.