MCQ
In the visible region the dispersive powers and the mean angular deviations for crown and flint glass prisms are $\omega , \omega '$ and $d, d' $ respectively. The condition for getting deviation without dispersion when the two prisms are combined is
- A$\sqrt {\omega d} \, + \,\sqrt {\omega 'd'} = 0$
- B$\omega 'd + \omega d' = 0$
- ✓$\omega d + \omega 'd' = 0$
- D${(\omega d)^2} + {(\omega 'd')^2} = 0$
