**JNTU Previous Papers B.Tech **

**Supplimentary Examinations, Aug/Sep 2008**

**INSTRUMENTATION**

**(Electrical & Electronic Engineering)**

**SET-I**

1. Define the following

(a) Arithmetic mean

(b) Median

(c) Standard deviation

(d) Variance.

2. (a) Explain about aperiodic signal with examples.

(b) Compare periodic and aperiodic signals.

3. Draw the block diagram of a sampling oscilloscope and describe its working with

necessary wave forms?

4. (a) Explain the basic circuit of a digital frequency meter.

(b) A 312 digital voltmeter is used for measuring voltage

i. Find its resolution

ii. How would the voltage of 14.53 v be displayed on 10 V scale?

iii. How would the voltage of 14.53 v be displayed on 100 V scale?

5. (a) What is a wave analyzer? Mention its significance in measurement system

(b) Explain the working of a Frequency selective wave analyzer with a neat block diagram.

(c) Mention few applications of heterodyne wave analyzers.

6. A piezoelectric transducer has a capacitance of 1000pF and a charge sensitivity of

40× 10 – 3 C/m. The connecting cable has a capacitance of 300pF while the oscilloscope used for readout has an input resistance of 1M and a parallel capacitance of 50pF.

(a) what is the sensitivity of the transducer alone?

(b) (V/m) of the entire measuring system?

(c) what is the lowest frequency that can be measured with a 5% amplitude error by the entire system

(d) what is the value of external shunt capacitance that can be connected in order to extend the range of 5% error down to 10 Hz.?

(e) What is the high frequency sensitivity, when the external shunt capacitance

calculated in

(f) is connected in the circuit.

7. Discuss the principle of operation , advantages and disadvantages of drag cup type tachogenerator.

8. (a) Mention various types of instruments used for temperature measurement.

(b) Describe the temperature measurement with resistance thermometers.