In an achromatic combination of two prisms, the ratio of the deviations produced by the two prisms is $2:3$, the ratio of their dispersive power is :

Q. If the ratio of dispersive powers of the materials of two prisms be $2:3$ and ratio of angular dispersions produced by them is $1:2$, then the ratio of mean deviation produced by them is:

Q. In an achromatic combination of two prisms made of materials with dispersive powers $0.2$ and $0.25$, if the angular dispersion produced by each prism is $100$, the net deviation is:

Q. Two prisms A and B have dispersive powers of 0.012 and 0.018 respectively. The two prisms are incontact with each other. The prism A produces a mean deviation of ${1.2}^{\circ }$, what is the mean deviation produced by B if the combination is achromatic?

Q. Two prisms A and B have dispersive powers of 0.012 and 0.018 respectively. The two prisms are incontact with each other. The prism A produces a mean deviation of ${1.2}^{\circ }$, what is the mean deviation produced by B if the combination is achromatic?

Q. Two lenses in contact form an achromatic lens. Their focal lengths are in the ratio 2 : 3. Their dispersive powers must be in the ratio of