1. 13.6 The Human Eye

3. The “shutter” http://upload.wikimedia.org/wikipedia/co mmons/a/a3/Eye_dilate.gif http://upload.wikimedia.org/wikipedia/co mmons/a/a3/Eye_dilate.gif

4. When the lens is stretched, it becomes thinner. Think of what happens if you pull on either side of a water balloon. This decreases the lens’ ability to change the light ray’s path. When the lens is not stretched, it becomes thicker. This increases the lens’ ability to change the light ray’s path.

5. The retina: the “film” When the light rays reach the back of the eye, it hits the RETINA which is composed of many ROD and CONE cells ROD cells are more sensitive to light and are used for night vision CONE cells are less sensitive to light (but can distinguish colour) and are used for vision during the day The retina contains blood vessels that keep the cells healthy

6. FOVEA: contains the highest concentration of cone cells - this area is responsible for processing most of the incoming light BLIND SPOT: contains no cone cells because all the blood vessels feeding the eye exit and enter here

7. A change of shape The energy of the light rays causes the cells to change shape This initiates an electric signal that travels towards the brain The brain then interprets this signal

8. STEREOSCOPIC VISION

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