Question

Find the ratio of mean deviation produced, if the ratio of dispersive power of the material of two prism are 2:3 and ratio of angular dispersions produced by them is 1:2.

(a) 1:3

(b) 4:3

(c) 3:1

(d) 3:4

I have been asked this question by my college professor while I was bunking the class.

Enquiry is from Dispersion, Fermat’s Principle & its Application in portion Optics of Engineering Physics II

Answer 1

The correct option is (d) 3:4

Best explanation: let ω be the mean deviation produced,

ω = (angular dispersion) / dispersive power

ω = (1:2 ) / (2:3)

therefore,  ω = 3:4.