JNTU B.Tech Supplimentary Examinations, Aug/Sep 2008
(Electrical & Electronic Engineering)
1. (a) How the performance characteristics of an instrument are classified?
(b) Explain clearly the difference between Accuracy and Precision?
2. (a) Explain the spectra of a periodic rectangular pulse train for the following.
(ii) Phase spectra when time origin coincides with centre of pulse.
iii) Phase spectra with pulse starting at t=0.
(b) Define line spectra.
3. Draw and explain different parts of a CRT?
4. Explain with neat circuit diagram the working of the linear ramp type DVM.
5. (a) Explain the working of a heterodyne wave analyzer with a neat block diagram.
(b) Explain the principle and operation of basic spectrum analyzer with a neat block diagram.
6. Explain the factors that influence the selection of a transducer.
7. (a) Describe the following methods of temperature compensation for strain gauges
i. use of dummy gauge
ii. half bridge method.
(b) A single electrical resistance strain gauge of resistance 120 and having a gauge factor of 2 is bonded to steel having elastic limit stress of 400MN/m2. and modulus of elasticity 200GN/m2.Calculate the change in resistance due to
i. change in stress equal to 1/10th of the elastic range
ii. change of temperature of 20 0C if the material is advanced alloy. The resistance temperature coefficient of alloy is 20 × 10 – 6/ 0C.
iii. Calculate the strain due to the differential expansion of the guage metal and steel, if coefficient of linear expansion of the steel is 12 × 10 – 6/ 0C and that of the advanced alloy is 16 × 10 – 6/ 0C.
8. (a) Describe the principle and operation of Knudsen gauge with a neat sketch.
(b) Describe the operation of Ionization gauges for pressure measurement.