The least distance of distinct vision for a young adult with normal vision is about:

The human eye can focus objects at different distances by adjusting the focal length of the eye-lens. This is due to:

The human eye forms the image of an object at its:

The change in focal length of an eye-lens is caused by the action of the:

A person needs a lens of power, -5.5 dioptres for correcting his distant vision. For correcting his near vision, he needs a lens of power +1.5 dioptres. What is the focal length of the lens required for correcting

(i) distant vision, and

(ii) near vision?