Sigma comparator is a type of ______________ comparator.

Explanation

Explanation: The purpose of all the comparator gauges is to indicate the difference in the size between the standard (slip gauge or ring gauge) and the work being measured by means of some form of pointer on a scale at a magnification which is enough to read to the level of accuracy required. The following principles are employed in the commonly used comparator gauges. Mechanical comparator Mechanical comparator employs mechanical means like levers, gear train etc. for magnifying all deviation of the measurement. Example: Johansson Mikrokator Sigma Comparator Mechanical - Optical Comparator ‘Red’ comparator Important Points Electronics comparator It works by using step up, step down transformers. The electrical comparator generally depends on the Wheatstone bridge principle. Electrical comparators have no moving parts. Thus, a high degree of reliability is expected from these instruments. Pneumatic comparator Pneumatic comparator works by using high-pressure air, valves, back pressure etc. It works on the principle of pressure difference generated by the air flow. This comparator is fast, rigid, accurate and suitable for use on the shop floor, especially in mass production. Optical comparator Optical comparator works by using a lens, mirrors, light source etc. These instruments employ the principle of reflection of light rays. Very large magnifications are attainable, and the instrument is free from friction and backlash. Accuracy of measurements up to 1μ is possible.