R050212201 Calibration And Electronic Measurements

Set No. 1

Code No: R050212201

II B.Tech I Semester Regular Examinations, November 2007 CALIBRATION AND ELECTRONIC MEASUREMENTS (Instrumentation & Control Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. A set of independent measurements were made to determine the weight of a lead shot. The weights in grams were 1.570, 1.597, 1.591, 1.562, 1.577, 1.580, 1.564, 1.586, 1.550, 1.575 Calculate (a) the arithmetic mean (b) the deviation from the mean (c) the average deviations (d) Standard deviation (e) Variance (f) Probable error of one reading (g) Probable error of mean

[16]

2. (a) What is the difference between secondary standards and working standards (b) Describe the international standard of mass and volume? (c) Explain the concept of inductance standards?

[4+4+8]

3. What are the different types of calibrations used and explain each of them? [16] 4. (a) A 10mA meter movement with an internal resistance of 100Ω is to be converted into a 0-100mA. Calculate the value of shunt resistance required? (b) State different types of thermocouples and explain the effect of frequency on thermocouples? [12+4] 5. (a) “ The Maxwell’s bridge is used for the measurement of medium. Q coils only” Justify this statement with suitable examples. (b) Draw a basic Q meter circuit and discuss how does it measure Q by direct connection method. [6+10] 6. (a) With the help of a block diagram explain the multiplexed display technique used in a frequency counter. (b) Explain in detail about frequency mode errors and period mode errors. [4+6+6] 7. (a) Describe the electrostatic focusing system of a CRT. (b) With a block diagram explain the operation of digital storage oscilloscope. [8+8] 1 of 2

Set No. 1

Code No: R050212201 8. (a) Explain common cathode seven segment display.

(b) With a neat sketch describe the operation of a potentiometric recorder. [8+3+5] ⋆⋆⋆⋆⋆

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Set No. 2

Code No: R050212201

II B.Tech I Semester Regular Examinations, November 2007 CALIBRATION AND ELECTRONIC MEASUREMENTS (Instrumentation & Control Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) Six determinations of a quantity as entered on the data sheet and presented for analysis are 12.35, 12.71, 12.48, 10.24, 12.63 and 12.58. Calculate i. the arithmetic mean ii. the deviation from the mean iii. the average deviation iv. Standard deviation. (b) Write the difference between accuracy and precision with examples. [12+4] 2. (a) Describe the international standard of mass, length and volume? (b) What are atomic standards for frequency and time?

[8+8]

3. (a) Explain the following terms: i. Accuracy ii. Bias iii. Calibration iv. Calibration interval (b) What are the things involved in calibration program?

[8+8]

4. (a) Write short notes on extending of ammeter and voltmeter ranges? (b) A 1mA meter movement with an internal resistance of 100Ω is to be converted into a 0-100mA. Calculate the value of shunt resistance required? [8+8] 5. (a) Explain how a Kelvin’s double bridge can accurately measure low resistances. Also derive the condition for balance. (b) In the Kelvin’s Bridge shown in figure 5b the ratio of Ra to Rb is 2000Ω,R1 is 10Ω and R1=0.2 R2. Calculate the value of Rx . [10+6]

Figure 5b 1 of 2

Set No. 2

Code No: R050212201

6. (a) Differentiate between absorption and transmission type wave meters. (b) With a neat sketch explain the operation of frequency selective wave analyzer. [8+8] 7. (a) Describe the electrostatic focusing system of a CRT. (b) What is the minimum distance L, that will allow full deflection of 4 cm at the oscilloscope screen with a deflection factor of 100 V/cm and with an accelerating potential of 2000 V ? [8+8] 8. (a) Draw the block diagram of a filter bank spectrum analyzer and explain its operation. (b) Write short notes on display systems. ⋆⋆⋆⋆⋆

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[3+5+8]

Set No. 3

Code No: R050212201

II B.Tech I Semester Regular Examinations, November 2007 CALIBRATION AND ELECTRONIC MEASUREMENTS (Instrumentation & Control Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. What are the three general classes of errors? Explain each class in detail?

[16]

2. Write short notes on any THREE standards: (a) Resistance (b) Voltage (c) Current (d) Capacitance

[16]

3. (a) What is reliability and explain the concept of measurement reliability? (b) Explain the calibration of DC and AC instruments?

[8+8]

4. (a) Draw the circuit of AC voltmeter using full wave & half wave rectifier and explain its working? What are the advantages of using full wave rectifier over half wave rectifier while measuring AC voltage? (b) Give the general specifications of DVM’s?

[12+4]

5. (a) Explain how a Kelvin’s double bridge can accurately measure low resistances. Also derive the condition for balance. (b) In the Kelvin’s Bridge shown in figure 5b the ratio of Ra to Rb is 2000Ω,R1 is 10Ω and R1=0.2 R2. Calculate the value of Rx . [10+6]

Figure 5b 6. (a) With a neat sketch explain the operation of frequency selective wave analyzer (b) With the help of a circuit diagram explain the working principle of an output power meter. [8+8] 1 of 2

Set No. 3

Code No: R050212201 7. (a) Explain the operation of 10 to 1 probe .

(b) A given oscilloscope has an input resistance of 10 M ohm shunted by 20 pf. Design a 10 to 1 probe. [8+8] 8. (a) Draw and discuss the spectral displays of various modulations using spectrum analyzer. (b) Explain the F M method of magnetic tape recording and explain its advantages and disadvantages. [8+6+2] ⋆⋆⋆⋆⋆

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Set No. 4

Code No: R050212201

II B.Tech I Semester Regular Examinations, November 2007 CALIBRATION AND ELECTRONIC MEASUREMENTS (Instrumentation & Control Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) Six determinations of a quantity as entered on the data sheet and presented for analysis are 12.35, 12.71, 12.48, 10.24, 12.63 and 12.58. Calculate i. ii. iii. iv.

the arithmetic mean the deviation from the mean the average deviation Standard deviation.

(b) Write the difference between accuracy and precision with examples.

[12+4]

2. (a) State the SI units, unit symbols and define each unit for the following i. ii. iii. iv.

Conductance Magnetic flux Flux density Inductance

(b) A bar magnet with a one inch square cross section is said to have a total magnetic flux of 500 Maxwell. Determine the flux density in tesla? [8+8] 3. (a) Explain the following terms i. ii. iii. iv.

Measurement and test equipment Traceability Reliability Tolerance limits

(b) Explain the procedure that should be followed before attempting to calibrate deflecting instruments? [8+8] 4. (a) Explain the working principle of AC voltmeter using full wave & half wave rectifier? (b) For the circuit (figure 4) shown calculate the AC and DC sensitivity?

1 of 2

[8+8]

Set No. 4

Code No: R050212201

Figure 4 5. (a) Discuss the problems associated in AC bridges if used for measurement at very high frequencies. (b) A Hay bridge is used to measure an inductive impedance.The bridge constants at balance are C1=0.1µF, R1= 20KΩ, R2= 5KΩ R3= 2KΩ and W=3000 rad/s. Calculate Lx, Rx. [8+8] 6. (a) With the help of a block diagram explain the multiplexed display technique used in a frequency counter. (b) Explain in detail about frequency mode errors and period mode errors. [4+6+6] 7. (a) Explain the operation of 10 to 1 probe . (b) A given oscilloscope has an input resistance of 10 M ohm shunted by 20 pf. Design a 10 to 1 probe. [8+8] 8. (a) Explain the operation of logic timing analyzer and logic state analyzer. (b) What are the merits and demerits of Magnetic recording? ⋆⋆⋆⋆⋆

2 of 2

[5+5+6]