A achromatic combination is made with a lens of focal length `f` and dispersive power `omega` with a lens having dispersive power of `2omega` . The focal length of second will be

To produce an achromatic combination a convex lens of local length 42 cm and dispersive power 0.14 is placed in contact with a concave lens of dispersive power 0.21. The focal length of the concave lens is

The power of a lens having a focal length of 1 cm is

The power of lens depends on the focal length of the lens

An achromatic lens-doublet is formed by placing in contact a convex lens of focal length 20 cm and a concave lens of focal length 30 cm. The dispersive power of the material of the convex lens is 0.8. Determine the dispersive power of the material of the concave lens. Calculate the focal length of the lens-doublet.

An achromatic lens-doublet is formed by placing in contact a convex lens of focal length 20 cm and a concave lens of focal length 30 cm. The dispersive power of the material of the convex lens is 0.8. Determine the dispersive power of the material of the concave lens. Calculate the focal length of the lens-doublet.

An achromatic lens -double is formed by in contact a convex lens of focal length 20 cm amd a concave lens of focal length 30 cm.The dispersive of the meterial of the convex lens is 0.18 (a) Determine the dispersive power of the meterial of the concave lens (b) Calculate the focal of the lens-doublet 0.27 (b) 60 cm