In a certain spectrum produced by a glass prism of dispersive power `0.0305,` it is found that the refractive index for the red ray is `1.645.`and that for the violet ray is `1.665`. What is the refractive index for the yellow ray?

Explanation

Here, `omega = 0.031 , mu_(r) = 1.645 mu_(v)= 1.665, mu_(y) = ?`
`because omega=(mu_(v)-mu_(r))/(mu_(y)-1) = therefore mu_(y)-1 = (mu_(v) - mu_(r))/(omega) = (1.665-1.645)/(0.031) = (0.020)/(0.031) = 0.645 therefore mu_(y) = 0.645+1 = 1.645`