JNTU B.Tech II Semester INSTRUMENTATION Examinations, Apr/May 2008
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
1. (a) How the performance characteristics of an instrument are classified?
(b) Explain clearly the difference between Accuracy and Precision? [8+8]
2. Describe the process of modulation and the techniques usually adopted. 
3. Discuss in detail, electrostatic deflection of the electron beam. 
4. What are the different types of Digital voltmeters? Explain them briefly with neat
5. (a) Explain the principle and working of true RMS voltmeter with a block diagram.
(b) What are the differences between peak reading and RMS voltmeters. [10+6]
6. (a) Discuss the materials used for potentiometers.
(b) A voltage dividing potentiometer is used to measure an angular displacement of 600 and the total angle travel of the potentiometer is 3550. Calculate the voltage output on open circuit if the potentiometer is excited by a 60V source. Calculate the actual value of the output voltage at this setting if a voltmeter of 1M resistance is connected across the output.The resistance of the potentiometer is 1K. Calculate the % error. [6+10]
7. (a) What is a load cell. Explain its principle of operation.
(b) A load cell consists of a solid cylinder of steel 40mm indiameter with four strain gauges bonded to it and connected into the four arms of voltage sensitive bridge. The gauges are mounted to have a Poisson’s arrangement. If the gauges are each of 100 resistance and gauge factor 2.1, the bridge excitation voltage 6V, determine the sensitivity of the cell in V/kN. Modulus of Elasticity of steel is 200GN/m2 and the poisson’s ratio is 0.29. [8+8]
8. (a) Discuss in detail about turbine meters including their advantages and limitations.
(b) Describe pressure measurement Piezoelectric transducers with neat sketches.