3. The Human Eye (biology)
The pupil is an opening which allows light to pass into the eye. It is
the dark hole in the center of your eye. The pupil is controlled by
the iris (the colored part of the eye) which is a muscle that contracts
to make the pupil smaller and relaxes to allow the pupil to widen.
The pupil’s size relates to how much light there is in a particular
setting. The iris is covered by the cornea. The lens of the eye is
located in back of the iris. The lens focuses the light onto the retina,
which acts like a screen. Eyelashes and eyelids protect the eye by
stopping dust particles from falling onto the eye itself.
4. The Human Eye (biology)
There are two types of light sensitive cells on the retina.
Rods, are used for black and white vision, and are
concentrated on the sides of the retina. Cones are used for
color vision, and are concentrated in the center of the
retina. Vision is most acute in the area of the retina known
as the fovea centralis.
6. The Human Eye (Physics)
In our eyes, the object is beyond 2F, and the image formed
is real, inverted, smaller than the object, and on the
opposite side of the lens. We know that the image formed
must be real, because it is projected onto the retina (which
is like a screen). However, we don’t actually “see” the
object as inverted because our brain flips things around so
that we see them as being upright.
7. The Human Eye (Physics)
We know that lenses are needed to focus an object onto a
screen, and in this case the retina. One of the theories of
how the eye focuses is the 3 lens system. In this situation,
(1) the cornea would have little refractive power, and just
serve as a “cover glass” to the eye. (2) The aqueous lens lies
on top of the pupil, and has a strong refractive power,
because it is a very thick lens. (3) The vitreous lens does a
lot of magnification.
8.
9. Other facts
Its index of refraction The blind spot, located
changes because there is where the optic nerve
a density change within meets the eye, contains
the lens itself. no photo-receptors.
Some animals have literal colour blindness.
They do not have cones on their retinas.
10. Sources:
Saskatchewan Education. (1992). Science: A
Curriculum Guide for the Secondary Level
Physics 20/30
Oracle Quest. Retrieved from
http://library.thinkquest.org/C003776/ingles
/print/chapter5.htm
