This set of Engineering Metrology Multiple Choice Questions & Answers (MCQs) focuses on “Uses of Comparators”.
1. Which of the following is true for uses of comparators?
a) Can’t be used in mass production
b) Not suitable for inspection purposes
c) Can be used as working gauge
d) Slow rate of working
Explanation: Comparators are used in mass production where components are checked at a fast rate. These can be used as inspection purposes, laboratory standards and working standards or gauges.
2. What is the principle of ‘The Johansson Mikrokator’?
a) Button spinning on a loop of string
b) Principle of interference
c) Optical magnification
d) Principle of transformer
Explanation: Johansson Mikrokator is a mechanical comparator used to obtain mechanical magnification. Principle of Johansson Mikrokator is ‘spinning of a button on a loop string’. Magnification of this comparator is of the order of 5000.
3. From which category ‘Sigma comparator’ belongs?
a) Optical comparator
b) Mechanical comparator
c) Mechanical-optical comparator
d) Pneumatic comparator
Explanation: Sigma comparator is a mechanical comparator. Components of sigma comparator are a plunger, knife edge, cross strip hinge, Y-shaped arm, driving drum, slit diaphragm, a scale and a pointer etc.
4. What is the advantage of mechanical comparator over others?
a) Less moving parts
b) No need of external supply
c) No error due to parallax
d) Large range of instrument
Explanation: Mechanical comparator is cheaper as compared to others. Mechanical comparators have more moving parts due to this friction is more and accuracy is less. External supply is not required. Moving pointer moves over a fixed scale hence error due to parallax is possible.
5. Which of the following is true for ’Cross strip’ in sigma comparator?
a) Has two moving members
b) Cross strip is hinged
c) Two members are at 45o to each other
d) A flexible strip is attached to any one of the members of cross strip
Explanation: A hinged cross strip is present in sigma comparator which has a fixed and a moving member. These are connected to by thin flexible strips and right angle to each other. External force is applied on the moving member.
6. Which colour of light is filtered by filter present in Zeiss Ultra-optimeter?
Explanation: Zeiss ultra-optimeter gives a high degree of magnification. This instrument has an optical system involves a double reflection of light. A green filter is present which filters all but the green light which is less fatiguing to the eye.
7. Which of the following is true for Eden-Rolt Millionth Comparator?
a) Utilise both mechanical and optical magnifications
b) Only mechanical magnification
c) Only optical magnification
d) Only electrical magnification
Explanation: Eden-Rolt Millionth is a comparator which utilizes both optical and mechanical magnification that means it can utilize advantages of both optical and mechanical comparators hence it is a highly sensitive comparator. Design of this comparator is economical and simple.
8. Which of the following option is correct regarding the characteristics of comparators?
a) Minimum inertia
b) Minimum compensation for temperature effect
c) High measuring pressure
d) Minimum versatility
Explanation: Design of the instrument must be such that it can be used for wide range of operations which means instrument must have highest versatility. Instrument should be free from wear effects and from backlash and inertia of the system should be minimum.
9. What is the use of bleed valve in flow type pneumatic comparator?
a) Zero adjustment
b) Measurement of size
c) Connect passage of air from plastic tube to gauging head
d) Used with pressure reducing unit
Explanation: Bleed valve in pneumatic comparator is used for zero adjustment. A screw is also present at the inlet of tapered glass tube by which magnification can be changed by passing some air supply from it.
10. What is the order of overall magnification in Eden-Rolt Millionth Comparator?
Explanation: Mechanical and optical magnification of this instrument is of the order of 400 and 50 respectively. Thus, the overall magnification of Eden-rolt millionth comparator is of the order of about 20,000.
Sanfoundry Global Education & Learning Series – Engineering Metrology.
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