http://www.ck12.org Chapter 22. Visible Light
Lesson Summary
- The structures of the human eye collect and focus light. They form a reduced, upside-down image on the
retina at the back of the eye. - The image focused by the eye travels through the optic nerve to the brain as electrical signals. The brain
interprets the signals and “tells” us what we are seeing. - Common vision problems include nearsightedness (myopia), which can be corrected with concave lenses, and
farsightedness (hyperopia), which can be corrected with convex lenses.
Lesson Review Questions
Recall
- How are the pupil and iris related?
- Which parts of the eye focus light?
- Describe the retina.
- What is the function of the optic nerve?
- In an eye with normal vision, where are images focused?
Apply Concepts
- Create a lesson for younger students to teach them how the eye works. With your teacher’s approval, present
your lesson to a class in a lower grade.
Think Critically
- Compare and contrast rods and cones.
- Why is the brain needed for vision?
- Identify a common vision problem and explain how lenses can be used to correct it.
Points to Consider
This chapter focuses on energy in the form of visible light. Another common form of energy, electrical energy, is
the focus of the chapterElectricity.
- What are some ways you use electrical energy?
- Where does the electrical energy you use come from?
ForTable22.1:
- Incandescent bulb: Olga Reznik. http://www.flickr.com/photos/belobaba/6058142799/. CC BY 2.0.
- Fluorescent bulb: Vasenka Photography. http://www.flickr.com/photos/vasenka/6635890033/. CC BY 2.0.
- Neon light: Brian Kelly. http://www.flickr.com/photos/y2bk/528300692/. CC BY 2.0.
- Vapor light: Robert Ashworth. http://www.flickr.com/photos/theslowlane/7967029974/. CC BY 2.0.