Engineering Metrology Multiple Choice Questions on “Conditions of Comparison”.
1. What is TEI?
a) UNDE+NDE+TVE
b) UNDE-NDE-TVE
c) UNDE+NDE-TVE
d) UNDE-NDE+TVE
Answer: a
Clarification: NDE is a nominal differential expansion, UNDE is an uncertainty of nominal differential expansion, TVE is temperature variation error. NDE is the difference between the nominal expansion of master and part.
2. What is the maximum limit of TEI after which attention is required?
a) 5% of the tolerance part
b) 10% of the tolerance part
c) 15% of the tolerance part
d) 20% of the tolerance part
Answer: b
Clarification: If the TEI is > 10% of the part of tolerance, then attention is required. In close tolerance works, thermal effect is a single largest source of error. Efforts like applying correction and air conditioning doesn’t always solve the problem.
3. Which of the option is correct about given statements factors affecting standards?
Statement 1: A uniform temperature is important in metrology labs.
Statement 2: Ambient temperature may change by convection, conduction and radiation.
a) Only statement 1 is correct
b) Only statement 2 is correct
c) Both the statements are correct
d) Both the statements are false
Answer: c
Clarification: A uniform temperature is necessary because rate of thermal expansion is different for different materials. Ambient temp may change by convection, conduction and radiation but the effect of radiations is more troublesome.
4. Up to which length of gauges, there is no appreciable change in length with a method of support?
a) 75 mm
b) 100 mm
c) 150 mm
d) 200 mm
Answer: a
Clarification: For small gauges upto 75 mm length, there is no appreciable change in length for a method of supports. But dimensions of long gauges may change even by their own weight.
5. What is the full form of TEI?
a) Total error index
b) Total expansion index
c) Thermal expansion instrument
d) Thermal error index
Answer: d
Clarification: Thermal error index can be reduced by establishing a more accurate coefficient of expansion, making corrections for NDE, minimizing temperature variation from 20 degree C.
6. What is the value of humidity in test laboratories for performing a measurement or any other operation?
a) 35±10%
b) 45±10%
c) 55±10%
d) 65±10%
Answer: b
Clarification: Lower RH value can invalidate measurement by building static charge. High value of RH can cause leakage. It should be maintained at 45±10%.
7. Which of the following statement is correct for given statements?
Statement 1: Nitra-alloy is an ultrastable material.
Statement 2: In steel coefficient of expansion can be increased by adding nickel.
a) F, F
b) F, T
c) T, T
d) T, F
Answer: d
Clarification: Metallurgic compositions also affect the stability of the material. Coefficient of expansion of steel can be reduced by adding nickel. It is desirable to have materials with the same coefficient of expansion.
8. Which of the following statement is not suitable to reduce error produced by temperature variation?
a) Increase rate of air flow
b) Increase the frequency of variation of temperature
c) Increase the amplitude of temperature variation
d) Redesign masters and comparators