Question

Under what condition white light bands appear when a comparison of lengths of two slip gauges takes place?

(a) Optical paths from dividing mirror are less

(b) Optical paths from dividing mirror are more

(c) Optical paths from dividing mirror are equal

(d) Optical paths from dividing mirror can be more or less

The question was posed to me in quiz.

This intriguing question originated from Checking of Slip Gauges in section Testing and Calibration of Gauges and Dynamic Measurement of Engineering Metrology

Answer 1

Correct answer is (c) Optical paths from dividing mirror are equal

The best I can explain: The standard gauge is adjusted so that the end faces of slip gauges are at an optical path distance from the dividing mirror when illuminated by the source of white light. Under these conditions the interference fringes appear are known as ‘white light band’. These are produced when the optical paths from the dividing mirror are same or equal.