1. Topic 12
Light

2. Lesson 4: The Eye

3. Experiences and Outcomes of Lesson
Identify the basic parts of an eye
State the function of the basic parts of an eye
Explain how an eye can form an image on a screen for objects at different distances

4. Parts of the Eye
Lens
Retina
Pupil
Link to Glow Science
Iris

5. Function of the Eye Part Function Iris Pupil Lens Retina
Controls the amount of light entering through the pupil by contracting or relaxing
Hole through which light enters the eye
Helps to make any fine adjustments to the focusing of the eye
Sends messages to the brain though the optic nerve.

6. Experiment
Aim: Investigate how changing the thickness of the lens affects the image that is formed at different distances.

7. Method: F shape for object Screen for image Convex lens
Changing thickness
Screen for image
FIXED IMAGE DISTANCE

8. If the object is close, the lens gets fatter as it tries to focus.
Results:
The eye lens is filled with jelly which becomes fatter or thinner as the eye tries to focus.
When the eye tries to focus on an object that is far away, the lens gets thinner as it tries to focus.
If the object is close, the lens gets fatter as it tries to focus.
As we get older, muscles weaken and it’s more difficult to do this.
Link to Glow Science

9. Extension
Click on the picture below to look at an animation of the effect of glasses on the eye.