Question

The focal length of the lens in the eye is controlled by
(A) Vitreous humor
(B) Ciliary muscles
(C) Iris
(D) Pupil

Answer 1

Hint:The eye is one of the most delicate and most valuable organs in the human body. It consists of many sub parts such as lens, nerves and some delicate tissues. The light enters in the eye and an image is formed on the retina which is situated at the last. The retina is connected to the brain through optic nerves and in the form of impulses the signal is carried to the brain.

Complete answer:
The lens shape is regulated with the help of ciliary muscles. These are a pair of muscles and their primary role is to relax or tighten the fibres that hold the lens to focus and enable the eyes to see clearly. They contract and relax in order to adjust the lens for optimum entry of light.

So, the correct option is B.

Note:The lens plays a very important role and it regulates the light and focuses on the retina. The lens converges the parallel beam of light onto a point called focus and distance of the optical centre of the lens to the focus is called the focal length of the lens. The change in the shape of the lens enables the regulation of the light entering and this change in the lens changes its focal length. The image formed on the retina is always real and hence the image formed is inverted.