Which type of lens is present in the upper part of a bi-focal lens?

Correct Answer: Concave

Subject: Physics

Spherical
Prism
Convex
Concave

Explanation: The upper part of a bi-focal lens consists of a concave lens, which is used to correct myopia (nearsightedness), while the lower part is made of a convex lens which corrects hypermetropia (farsightedness). Extra info: This lens was invented by Benjamin Franklin. Individuals suffering from presbyopia are advised to use bifocal lenses.