1. pg. 506 - 511

2.  The Eyeball The Eyeball

3.  Iris: coloured part of the eye that opens and closes to let in more or less light. In the centre you find the pupil  Pupil: opening where light enters the eye  Cornea: Transparent bulge on top of the pupil

4.  Lens: Clear part behind the iris ◦ NOTE: Both the cornea & lens focus light & cause it to converge on the back of the eye.  Retina: Inner lining of eye that is made of light-sensitive cells, called rods and cones. These cells receive light rays, process them & send electric signals to the optic nerve

5.  Optic Nerve: The nerve at the back of the eye that is attached to the retina. It transmits the electrical impulses from the retina to the brain ◦ Since there are no light sensitive cells here, it creates a blind spot but each eye compensates for the other

6.  Light entering our eyes is refracted  The lens acts like a converging lens that produces a smaller, real, inverted image on the retina.  Electrical impulses travel through the optic nerve to the brain  Brain flips the inverted image so what we see is upright

7.  Accommodation is the changing of shape of the lens by ciliary muscles to allow a sharp focused image to form on the retina  By changing the eye’s shape, the focal length changes, allowing us to focus on distant and nearby objects

8.  Accommodation does not always work well. This results in an inability to focus on objects and thus producing blurred vision

9.  Inability to focus light from nearby objects (can see distant objects)  Light is focused behind the retina  Caused by a thin cornea; or an eyeball that is too short

10.  Corrected using converging contact lenses or eye glasses to help refract the light  A modified form of the converging lens, called a positive meniscus is used because it is thinner & more visually appealing than a basic converging lens

11.  Form of far-sightedness caused by a loss of accommodation as a person ages  Eye loses its elasticity as we grow older  Corrected using glasses with converging lenses

12.  Inability of the eye to focus light from distant objects (can see nearby objects)  Light is focused in front of the retina  A modified form of the diverging lens, called a negative meniscus, is used

13.  blurred or distorted vision  caused by an incorrectly shaped cornea  corrective lenses or laser eye surgery can be used to correct astigmatism

14.  Read pg. 506 - 511  Do #5, 7, 8 on pg. 511  Study for your Physics Unit Test (Chapters 10, 11, 12)