The human lens focuses light on the photoreceptor cells by:

• A. moving closer to the retina
• B. changing its shape to adjust focal length
• C. reflecting light away from the retina
• D. absorbing excess light before it reaches the retina

Answer: (B)

Verified step by step guidance

1. Understand the function of the human lens: The lens is a transparent, flexible structure in the eye that focuses light onto the retina, where photoreceptor cells detect the light and send signals to the brain.
2. Recognize the mechanism of focusing: The lens changes its shape to adjust the focal length, a process called accommodation. This allows the eye to focus on objects at varying distances.
3. Clarify why the lens does not move closer to the retina: The lens remains in a fixed position within the eye, and its ability to focus light is due to its shape-changing property rather than physical movement.
4. Explain why the lens does not reflect light away from the retina: The lens is designed to refract (bend) light toward the retina, not reflect it away. Reflection would prevent proper vision.
5. Discuss why the lens does not absorb excess light: The lens is transparent to allow light to pass through. Absorbing light would reduce the amount of light reaching the retina, impairing vision.