3a.3 - The Eye and Total Internal Reflection Flashcards
What is the cornea? (2)
- A transparent ‘window’ with a convex shape
- And a high refractive index
What does the cornea do?
Most of the eye’s focusing
What is the iris?
Made up of muscles that control the size of the pupil
What does the iris do?
Controls the intensity of light entering the eye
What is the lens? (2)
- Connected ciliary muscles by suspensory ligaments
- When the ciliary muscles contract, tension is released
What does the lens do?
Changes shape to focus the light from objects at varying distances
What is the retina?
Covered in light-sensitive cells
What does the retina do?
The cells detect light and send signals to the brain to be interpreted
Describe what is meant by the near point of the eye?
The closest distance the eye can focus on
Is the image on a camera real or virtual?
Real
What is the near point of the eye? (2)
- The closest point the eye can see
- Approximately 25cm
Describe how the eye focuses on objects at various distances (3)
- The ciliary muscles contract or relax
- To change the shape of the lens
- To focus at different distances on the retina
What eye condition can be caused by the cornea being too powerful?
Short sightedness
What type of lens can be used to correct long sightedness?
Converging
Suggest two ways shortsightedness can be corrected
Put a diverging lens in front of the eye
Remove corneal tissue using a laser