The focal length of a convex lens for red and violet colours is 26 cm and 25 cm respectively. Find focal length of the lens for the mean colour

Define focal length of a lens

If f_v and f_r are the focal lengths of a convex lens fro violet and red light respectively and F_v and F_r are the respective focal length of a concave lens,then we must have

Find the focal length of convex mirror whose radius of curvature is 32 cm.

The focal length of a coverging lens is measured for violet,green and red colours.It is f_v,f_g and f_r respectively.We will get

The radii of curvature of the faces of a double convex lens are 10 cm and 12 cm respectively.If the focal length of the lens is 12 cm ,find the refractive index of the material of the lens.

The focal length of a concavo - convex lens of radii of curvature 5 cm and 10 cm is 20 cm.What will be its focal length in water (mu=4//3) ?

What is the focal length of a convex lens of focal length 30cm in contact with a concave lens of focal length 20cm? Is the system a converging or a diverging lens? Ignore thickness of the lenses.

The radius of curvture of the convex face of a plano-covex lens is 12 cm and its refractive index is 1.5. Find the focal length of the lens. .