If two prisms are combined , as shown in figure, find the total angular dispersion and angle of deviation suffered by a white ray of light incident on the combination.

Explanation

Net angular dispertion
`= (delta_(V) - delta_(t)) - (delta'_(v) - delta'_(t))`
`= (mu_(v) - mu_(f))A - (mu'_(v) - mu'_(r)) A'`
`= (1.5+1.4)xx4^(@) - (1.7-1.5)xx2^(@) = 0`
Angle of deviation `= ((mu_(v) + mu_(r))/(2)-1) A - ((mu'_(V) + mu'_(r))/(2) - 1)` A'
`= ((1.5+1.4)/(2)-1) xx 4^(@) - ((1.7+1.5)/(2)-1) xx2^(@) = 0.6^(@)`