1.7 The Eye

Question 1

What is your cornea?

Answer 1

Transparent layer where light enters eye, it protects the eye and starts focusing the light onto the retina

Question 2

What is your iris?

Answer 2

Coloured ring of muscle that controls the amount of light that can enter the eye

Question 3

What is your pupil?

Answer 3

The central eyehole formed by the iris where light enters the eye

Question 4

What is your eye lens?

Answer 4

Focuses light into the retina

Question 5

What are your ciliary muscles?

Answer 5

Muscles attached to the lens any suspensory ligaments, they work to change the thickness of the lens to focus objects

Question 6

What is your optic nerve?

Answer 6

Carries nerve impulses from the retina to the brain

Question 7

What is the blind spot?

Answer 7

The point where the optic nerves connect to the retina, no light sensitive cells there so no images is formed there

Question 8

Explain the 6 step process of how our eyes form images in our brain?

Answer 8

1. The eye senses light and alters iris size to limit amounts of light into your eye
2. Ciliary muscles change the thickness of the lens
3. The lens focuses light onto the retina and forms a real image
4. Light sensitive cells in the retina change image into electrical impulses
5. Electrical impulses to the brain along the optic nerve
6. The brain processes the impulses and reforms the image

Question 9

What is the range of vision for a normal human being?

Answer 9

25cm to infinity

Question 10

Calculation for the power of a lens

Answer 10

P=1/f

Where p is the power in dioptres
F is the focal length in metres

Question 11

-D means power for what type of lens?

Answer 11

Diverging lens

Question 12

+D means power for what type of lens?

Answer 12

Converging lens

Question 13

What is short sightedness called?

Answer 13

Myopia

Question 14

What is long sightedness called?

Answer 14

Hypermetropia

Question 15

What is myopia?

Answer 15

Where the image is formed before reaching the retina

Question 16

What is hypermetropia?

Answer 16

Where the image focuses after the retina, not on the retina

Question 17

What causes myopia?

Answer 17

Fat lens, due to oval eyeball, weak ciliary muscles, eyeball too long, too powerful lens

Question 18

What causes hypermetropia?

Answer 18

Thin lens, due to thin eyeball, strong ciliary muscles, eyeball too short, eye lens too weak

Question 19

How can myopia be corrected?

Answer 19

Diverging lens, so the rays can be focused by the eye lens precisely

Question 20

How can hypermetropia be corrected?

Answer 20

Converging lens so it refracts perfectly on the retina

Question 21

What is the retina?

Answer 21

Light sensitive cells at the back of your eye where your lens focuses the light rays to form an image