P3 - The Eye Flashcards
What is the iris and what does it do?
The coloured part of the eye.
It controls pupil size to control light intensity entering the eye.
What does the eye’s lens do?
It changes shape depending on the object’s distance.
How does the eye’s lens work?
The ciliary muscles contract, releasing tension and making the lens more spherical.
The ciliary muscles relax, the dispensary ligaments pull the lens flat.
Where are images formed in the eye?
On the retina, which is covered in light-sensitive cells which send signals to the brain.
What is the far point?
The furthest distance that the eye can focus comfortably.
What is the far point for normally-sighted people?
Infinity.
What is the near point?
The closest distance the eye can focus on.
What is the approximate adult near point?
25cm.
What happens as the eye focuses on closer objects?
Its power increases - the lens changes shape and the focal length decreases.
What is the cornea and what does it do?
A transparent convex-shaped window with a high refractive index.
It focuses the eye.
Describe the image formed on a camera [3].
1) it is real.
2) it is smaller.
3) it is inverted.
What is the film or CCD in a camera equivalent to and how?
The retina - a real, inverted image is formed on them and adjusted.
