Question

In optical arrangement with graduated scale, when glass block is tilted by ‘i’ then incident ray from scale deviates from straight line path. What is the displacement ‘h’? ( w is the glass width)

(a) sin(i-r)/wcosr

(b) w cos(i-r)/sinr

(c) w sin(i-r)/cosr

(d) cos(i-r)/wsinr

The question was asked during an interview for a job.

I'm obligated to ask this question of Graduated Scales in division Linear Measurements of Engineering Metrology

Answer 1

The correct choice is (c) w sin(i-r)/cosr

The explanation: Scale division is sensed in the same position when optical axis and glass block are perpendicular to each other. Then it travels a straight line. But when glass block is tilted then incident ray is refracted by ‘r’.