Question

What is the ability of an eye lens to adjust its focal length called?

Answer 1

Hint: We can focus our eye on the distant images or near objects by the process of changing the lens. This process is very important to the eye. Identify that process so that you can understand the ability of the eye lens to adjust its focal length.

Complete step by step solution:
The process which is the ability of the eye lens to adjust its focal length is called “accommodation”. Generally, this process is completely taking place by the action of ciliary muscles. It changes the focal length of the eye lens. The ciliary muscles squeeze and contract the lens for getting a clear picture of the nearby objects whereas it relaxes and gets back to its flatter shape in case of distant objects. Unit of lens power is “dioptre”. A normal person can have the power accommodation around 4 dioptres.
Power of accommodation:
Power of accommodation can be defined as the maximum variation or change of its power for focusing on nearby objects as well as far objects.
Additional information:
Lens power depends on the focal length. As by adjusting the focal length, the eye automatically changes its lens power.

Note: The ciliary muscles affect the focal length of the lens as they are capable of modifying the curvature of the lens. For a young person who has a normal vision, experience the nearest point at 25 cm from the eye and the far point can be considered as infinity. The curvature of the lens in the eye is controlled by ciliary muscles. We can achieve maximum focal length when muscles are completely relaxed.