Question

Why does the eye need to change the focal length of the eye lens?

• A. To neglect the chromatic aberration
• B. When object distance changes, to form the image at retina
• C. As the position of retina keeps on changing
• D. To keep the eye clean and active

Answer 1

The correct option is B

When object distance changes, to form the image at retina

The dimension of eye is fixed so, the position of retina is fixed. For focusing on objects at various distances and getting their images at retina itself we need to change the focal length of the eye lens. Ciliary muscles does that by contracting and expanding.