A double convex lens has 10cm and 15cm as its 2 radii of curvature. The image of an object placed 30cm from the lens is formed at 20 cm from the lens on the other side.
Find the refractive index of the material of the lens.
What will be the focal length ?
What will be the focal length of the lens if it is immersed in water of RI 1.33?