Unit 3 - The eye

Question 1

What is the cornea

Answer 1

• The hard outside surface
• Protects the eye
• Refracts light
• Convex shape
• High refractive index

Question 2

The Iris

Answer 2

Controls the amout of light that enters the eye (dialates and contracts)

Question 3

The pupil

Answer 3

Where light enters

Question 4

The lens (also how its connected)

Answer 4

The lens focus’ light

Connected to the ciliary muscles by the suspensory ligaments

Question 5

What do the ciliary muscles do

Answer 5

Changes the shape of the lens and the focal length

Question 6

What happens when the Ciliary muscles contract

Answer 6

Tension is released and the lens turns into a more spherical shape

Question 7

What happens when the Ciliary uscles relax

Answer 7

The suspensory ligaments pull the lens into a thinner, flatter shape

Question 8

The retina

Answer 8

Images are formed here (its covered in light sensitive cells - these detect light and send signals to the brain to be interpreted)

Question 9

The Optic Nerve

Answer 9

Sends electrical signals to the brain

Question 10

What is the Sclera?

Answer 10

White and opaque to prevent light entering the eye

Question 11

The near point

Answer 11

The closest point at which an object can be seen clearly

Question 12

The farpoint

Answer 12

The furthest than an object can be seen clearly

Question 13

What is long sightedness?

Answer 13

When someone can’t focus clearly on close object because the image is formed behind the retina

Question 14

What are some reasons for long sightedness

Answer 14

• Lens is too weak
• Cornea may be too flat
• Eyeball may be too short

Question 15

Solutions to long sightedness?

Answer 15

Use a convex lens so rays focus on the retina (to bend the rays more)

Question 16

What is short sightedness

Answer 16

Some can’t focus clearly on distant objects because the image is formed infront of the retina

Question 17

What are some reasons for short sightedness?

Answer 17

• Lens can’t focus properly
• Eyeball is too long
• Cornea too curved

Question 18

Solution to short sightedness?

Answer 18

Use a concurve lens

Question 19

Why do older people wear glasses?

Answer 19

• Eye lens becomes less flexible
• Ciliary muscles weaken
• Range of distance changes

Question 20

For both the eye and the camera: Light enters through..

Answer 20

Eye: Pupil

Camera: Glass filter

Question 21

For both the eye and the camera: The lens is protected by..

Answer 21

Eye: Cornea

Camera: Glass filter

Question 22

For both the eye and the camera: The amount of light coming in is controlled by..

Answer 22

Eye: Iris

Camera: Adjustable apendature

Question 23

For both the eye and the camera: The light is focussed by the..

Answer 23

Eye: Lens

Camera: Glass lens

Question 24

For both the eye and the camera: Light is kept out by..

Answer 24

Eye: Sclera

Camera: Lightproof box

Question 25

For both the eye and the camera: Inside, light travels through the…

Answer 25

Eye: Vitreous humor

Camera: Air

Question 26

For both the eye and the camera: The image is focussed onto the..

Answer 26

Eye: Retina

Camera: Image sensor