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VTU Mechanical Engineering (Semester 3)
Mechanical Measurement and Metrology
June 2014
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

1 (a) Briefly explain:
i) International prototype metre
ii) Reference standard
iii) Wringing phenomenon
iv) Significance of wavelength standard.
8 M
1 (b) What are Airy points? Explain in detail.
4 M
1 (c) Using NPL method, derive equation for calibrating end standard from line standards.
8 M

2 (a) What are the concepts of interchangeability and selective assembly? Which is advantageous?
6 M
2 (b) Briefly explain:
i) Go-gauges, ii) NO-GO gauges, iii) Gauge tolerance and wear allowance.
6 M
2 (c) Determine the tolerance on the hold and shaft for a fit designated by 50H7g6, diameter step 50 to 80 mm; fundamental deviation for shaft=-2.5 D0.34 in micron; 1T6=10i and IT7=16i; i=0.45 $\sqrt[3]{D} +0.001D$ in micron. State the actual maximum and minimum size of the hole and shaft and maximum and minimum clearances.
8 M

3 (a) What are comparators? How do they differ from measuring instruments?
6 M
3 (b) Explain the principle of sine bar.
6 M
3 (c) Explain with sketch, the construction and working of LVDT.
8 M

4 (a) What is the principle of interferometry? How is it adopted in optical interferometer?
6 M
4 (b) Derive an expression for the chordal tooth thickness of gear.
6 M
4 (c) Explain 3-wire method of measuring effective diameter of screw thread.
8 M

5 (a) What is the significance of measurement?
4 M
5 (b) Explain the three stages of generalized measuring method using any one example.
8 M
5 (c) Differentiate:
i) Sensor and transducer
ii) Primary and secondary transducer
iii) Accuracy and sensitivity
iv) Error and correction
8 M

6 (a) What is the necessity of modifying devices? What are the advantages of electrical modifying devices?
6 M
6 (c) With a block diagram, explain the working of an x-y plotter.
8 M

7 (a) Briefly explain how pressure can be measured with elastic transducer.
6 M
7 (b) What are the methods of force measurement? Give examples.
6 M
7 (c) Explain with a neat sketch prony brake dynamometer.
8 M

8 (a) Explain the working principles of radiation pyrometer and thermocouple.
8 M
8 (b) Briefly explain: i) Strain gauge material; ii) Strain gauge factor; iii) Thermocouple material.
12 M

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