The eye

• Natuurkunde
• Middelbare school
• havo, vwo
• Leerjaar 2,3

The eye

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You can name different parts of the eye

You can explain the difference between the yellow -and blind spot 

You can explain these parts: cornea, pupil, iris, lens and eye nerve. 

You know the difference between rods and cones

You can explain what you need to be able to see an object

You know what is meant by accomodating the eye lens

Eyes

The eye

cross section 2

2

cross section 3

3

zooming in

4

cross section 1

retina(1), choroid(2), 

vitreous chamber (3), 

macula (4), blind  spot (5), 

eye nerve & artery +vein(6), eye muscle (7), 

sclera (8), 

cornea (9), iris (10), 

anterior chamber (11), 

lens (12), internal

eyemuscles (13)

1

Rods

Cones

retina

The retina consist mainly of light sensitive cells: the rods and cones

Rods

Rods are sensitive to  light intensity

There are about 120 miljoen rods

Cones

Cones are used to distinguish kleur. 

There are about 7 miljoen cones 

As a precondition there should be enough light present.

Macula

The yellow spot, or macula in the middle back of your eye is very sensitive for color because in this spot there are a lot of cones, there are cones elsewhere but much less. This means that you can only see color very well if you look straight at an object.

eyepatch

Did you know an eyepatch was used by pirates to be able to see better in darkness?

Just cover your own eye for a couple of minutes before you go to bed. 

Walk to your room without any light switched on and then remove the eyepatch. You will then notice that the covered eye is now highly sensitive for any light while your other eye seems to be totally blind. For more info take a look at Willem Wever

Looking in the dark

Since in the yellow spot (macula) there are mainly a lot of cones, it is not very suitable to differentiatie between dark and light area's. Therefore it is recommended to not look directly at the object you want to see, That way the lightrays will hit the area next to the macula and then the light will be picked up by the rods present. This makes you see better in the darkness.

Blind spot

The blindspot is situated at the spot where the eye nerve and bloodvessels are leaving the eye. In this spot there are no rods or cones and therefore you can't detect light or color when the light is hitting the blindspot after entering the eye through the cornea and lens.

eyebrow

glands

sclera

pupil

iris

eyelid

eyelashes

tear duct

Jigspace

1. Work together
   
2. Install the app - jigspace
   
3. Search for the eye
4. Study the cross section of the eye
   and make a drawing in your notebook

Compatibility:

- iPhone 6 of later

- iPad 6th generation

- iPad pro

How does a tv set work?

A tv set only uses 3 colors;

rood groen en blauw

So for yellow light it sends out
green and red light.. your brain

does the rest.

Bekijk mij van een afstandje.
Wat valt je op?

Field of view

The field of view is the area you can see without moving your head or eyes for that matter.

As you can see, the field of view depends on the type of animal.. being prey or predator.

You can enlarge your field of view using mirrors, like in a car.

Prey or predator?

If prey, then you need to be able to flee quickly if there is danger. Therefore their eyes are situated more to the sides of their faces. 

Predators can be recognized by the fact that their eyes are situated more to the front of the face. This causes more overlap between the two eyes which is very good to see depth which enables the preadator to make a good estimnate of the speed and distance of the object it is chasing.|

blind spot

Draw a cross and a circel 15 cm apart.

Then read the instructions.

instruction

1. cover your left eye and look at the circel.
2. Move your head slowly away from the circel until the cross dissapears. If it does the reflected light from the cross is hitting      your blindspot and then it can't be noticed anymore.

Where is your blind spot?

What is your field of view?

Bekijk dit krantenartikel eens

instructie

Controleer of je met je linkeroog aan de buitenzijde tot 90 graden kan zien en aan de binnenzijde tot 60 graden. Doe hetzelfde daarna omgekeerd met je linkeroog

cover your right eye

Put up your left thumb

Move your hand to the extremes to find out the limits of your field of view

Am I colorblind?

1

2

3

4

Do I need glasses?

1. Measure the width of the example on your screen
2. Multiply this distance 25 times and look at your screen from that distance
3. Look at the screen alternatingly with your left or right eye.

If you can see all letters or signs, then your vision is good.

1. Measure the width of the example on your screen
2. Multiply this distance 25 times and look at your screen from that distance
3. Look at the screen alternatingly with your left or right eye.
4. If you can see all letters or signs, then your vision is good.

1. Cover one eye and look at the whole picture
2. Can you see the black dot in the middle?
3. Can you see the whole roster while looking at the dot?
4. Are the lines of the roster black?
5. Are all lines of the roster seem parallel to you?

Check 

your 

retina

Do I have

astigmatisme?

1. Look at the 4 circels one after the other
2. Do you see even, clear black lines?

If this is not the case, when the lines are not straight or look a bit greenlike you may suffer from astigmatisme.