Question

The action of which of the following changes the focal length of the eye lens?

• A. Pupil
• B. Retina
• C. Ciliary muscle
• D. Iris

Hint:

Remember that the iris controls light entering via the pupil, while ciliary muscles control the lens shape for focusing.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The human eye can focus on objects at varying distances by changing the shape of its crystalline lens.
This ability is called the accommodation of the eye.

Step 2: Detailed Explanation:
The ciliary muscles are attached to the eye lens.
When these muscles contract or relax, they change the curvature of the lens, thereby altering its focal length to focus on near or distant objects respectively.

Step 3: Final Answer:
The ciliary muscle is responsible for changing the focal length.