Which lens is used to rectify the vision defect, hypermetropia ?

How will you calculate the focal length of a biconvex lens that is used to correct the defect f hypermetropia ? Explain it mathematically.

Which lens is used for the correction of hypermetropia ? And why ?

Which lens can be used to correct the vision defect given in the above figure ?

A concave lens is used to rectify… .

A double concave thin lens made out of glass (mu=1.5) have radii of curvature 500cm. This lens is used to rectify the defect in vision of a person. The far point of the person will be at

A double concave thin lens made out of glass (mu=1.5) have radii of curvature 500cm. This lens is used to rectify the defect in vision of a person. The far point of the person will be at

Uma cannot able to see the nearer objects clearly, but can see the far objects which lens is very useful to correct his vision defect ?