Question

Question #69a13

Answer 1

Dispersive power `omega` of a prism is related with the angle of deviation of blue ray `delta_b` and angle of deviation of red rays `delta_r` as follows

`omega=(delta_b-delta_r)/((delta_b+delta_r)/2)`

So dispersive power of 1st prism

`omega_1=(12-10)/((12+10)/2)=2/11`

And dispersive power of 2nd prism

`omega_2=(10-8)/((10+8)/2)=2/9`

So ratio of dispersive powers is

`omega_1:omega_2=2/11:2/9=9:11`