How does the mammalian eye focus an image? In your description, name the important physical structures in image formation, define the focal point, and explain what accommodation is and why it is important

Question

What will be an ideal response?

Answer 1

Answer: To create a clear image, light entering the eye must converge on a single point called the focal point, and this focal point must fall on the retina. However, light rays entering the eye are not always entering from the same direction. That is, light rays entering from a distant object are parallel when they strike the eye, but light rays entering from a nearby object are not parallel but are instead divergent. These light rays are bent once they hit the cornea and lens, and the light rays will converge. However, based on the difference in angles between distant and nearby objects, the light rays converge at different points beyond the lens. Light rays from distant objects have a short focal length (focal length: the distance from the center of a lens to its focal point). Light rays from nearby objects have a long focal length. In order to adjust the focal length and force the focal point onto the retina, a process called accommodation, the lens must change shape.

Additional information:
? The cornea and the lens have a convex shape, which causes light rays to bend toward each other. While both of these structures contribute to image formation, the cornea is not capable of changing shape to fine-tune image formation.
? The point where the light converges after passing through the lens is called the focal point.
? Accommodation is the process by which the eye changes its focal length to ensure that the focal point falls on the retina. In mammals, this happens when the lens changes shape. This change is a function of the contraction or relaxation of the ciliary muscles of the eye, to cause the lens to become more rounded or flattened, respectively.