JNTU II B.Tech I Semester Regular Examinations, November 2008
CALIBRATION AND ELECTRONIC MEASUREMENTS
(Instrumentation & Control Engineering)
1. (a) Briefly discuss, with examples, the following:
i. Point accuracy
ii. Accuracy as ‘Percentage of scale range’
iii. Accuracy as ‘Percentage of true value’.
(b) Discuss the following with respect to precision of a measurement:
ii. Number of significant figures.
2. (a) Describe the construction of resistance standard.
(b) Discuss the techniques used to minimize the errors in them.
3. Explain routine calibration in detail.
4. (a) Explain the ohmmeter part of an electronic multimeter.
(b) With a neat diagram showing the circuit arrangement explain how a multirange electronic ohmmeter is constructed using a switching arrangement.
5. List and Discuss the principle applications of Anderson’s bridge. A 1000 Hz bridge
has the following constants: arm ab, R1=1000 ohm in parallel with C1 = 0.5?F; arm bc,R3 =1000 ohm in series with C3 = 0.5?F; arm cd L4 = 30 mH in series with R4 = 200 ohm. Find the constants of arm da to balance the bridge. Express the result as a pure resistance R in series with a pure inductance L or capacitance C.
6. Draw the logic diagram of a time base for a frequency counter and explain.
7. What effect does increasing the writing rate of an Oscilloscope by increasing the accelerating potential have on the deflection sensitivity?
8. Explain recording power, frequency instabilities and dynamic range spectrum analyzer.