JNTU Question Papers-B.Tech-Instrumentation Supplementary Examinations-Aug/Sep 2008

JNTU B.Tech Supplementary Examinations, Aug/Sep 2008

INSTRUMENTATION

(Electrical & Electronic Engineering)

SET-IV

1. Draw the block diagram of the measuring system and explain the each stage with their functions.

2. Distinguish between analog modulation and digital modulation and explain the situations under which each is preferred.

3. (a) What do you mean by multi trace with respect to oscilloscopes?

(b) With a neat block diagram explain the each block of a dual-trace oscilloscope

4. (a) Write short notes on:

i. Resolution in digital meters

ii. Sensitivity of digital meters

(b) A 4 12 digit voltmeter is used for voltage measurements.

i. Find its resolution

ii. How would 12.98 volts be displayed on 10 volt range?

iii. How would 0.6973 be displayed on 1 volt range?

iv. How would 0.6973 be displayed on 10 volt range?

5. (a) Discuss in detail about the principle of operation of a capacitive transducer?

(b) What is the relation between sensitivity and area of plates?

6. Explain in detail about piezo electric transducer

7. (a) Explain the construction of different types of strain gauges with neat sketches.

(b) Explain in general how pressure is measured with electrical transducer as secondary transducers.

8. (a) Explain the principle of measurement of torque using magneto-strictive transducer.

(b) A mild steel shaft is used to connect a motor drive to a constant load torque. A foil strain gauge having a resistance of 120 and a gauge factor 2 is mounted on a shaft with its active axis at angle of 45 degrees to the axis of the shaft. The shear modules of steel is 80GN/m 2, the shaft radius is 15mm and the change in strain gauge resistance due to the load 0.24 . Find the load torque.