How the Human Eye Perceives Light

Study Notes

The human eye functions like a converging lens, also known as a convex lens
A lens is a curved, transparent material that refracts light in a predictable way
Mirrors reflect light, while lenses refract it

Converging (Convex) Lens: Parallel light rays passing through converge at a focal point
Diverging (Concave) Lens: Parallel light rays passing through spread apart, never meeting

Light enters the eye through the cornea, then passes through the pupil
The iris controls the size of the pupil, regulating the amount of light entering
The light then passes through the lens, which refracts the light again
The image is projected onto the retina, which acts as a projection screen
The brain inverts the image on the retina, making it right-side up

Cornea: Outer surface of the eye, thin like a credit card, allowing light to enter, and heals if scratched
Pupil: Dark, circular opening that allows light to pass through
Iris: Coloured part of the eye, a circular band of muscle that controls the size of the pupil, regulating the amount of light that enters
Lens: Refracts light again after passing through the pupil, Focuses light onto the retina, Its shape changes to focus on near/far objects
Retina: Lining at the back of the eye acting as a projection screen for incoming light rays; the brain inverts the image, creating a right-side-up view
Ciliary Muscles: Adjust the shape of the lens to focus on near and far objects
Optic Nerve: Carries the electrical impulses from the retina to the brain, where the image is processed

Farsightedness (Hyperopia): Distant objects are clear, but close-up objects are blurry; a converging lens corrects this
Nearsightedness (Myopia): Close objects are clear, but distant objects are blurry; a diverging lens corrects this