1. Light is associated only with either a source or its effects. Light is not considered to exist independently in space; and hence, light is not conceived of as "travelling".
2. An object is "seen" because light shines it. Light is a necessary condition for seeing an object and the eye.
3. Lines drawn outward from a light bulb represent the "glow" surrounding the bulb.
4. A shadow is something that exists on its own. Light pushes the shadow away from the object to the wall or the ground and is thought of as a "dark" reflection of the object.
5. Light is not necessarily conserved. It may disappear or be intensified.
6. Light from a bulb only extends outward a certain distance, and then stops. How far it extends depends on the brightness of the bulb.
7. The effects of light are instantaneous. Light does not travel with a finite speed.
8. A mirror reverses everything.
9. For an observer to see the mirror image of an object, either the object must be directly in front of the mirror, or if not directly in front, then the object must be along the observer's line of sight to the mirror. The position of the observer is not important in determining whether the mirror image can be seen.
10. An observer can see more of his image by moving further back from the mirror.
11. The mirror image of an object is located on the surface of the mirror. The image is often thought of as a picture on a flat surface.
12. The way a mirror works is as follows: The image first goes from the object to the mirror surface. Then the observer either sees the image on the mirror surface of the image reflects off the mirror and goes into the observer's eye.
13. Light reflects from a shiny surface in an arbitrary manner.
14. Light is reflected from smooth mirror surfaces but not from non-shiny surfaces.
15. Curved mirrors make everything distorted.
16. Light shines on a translucent material and illuminates it so it can be seen. Light does not travel from the translucent material to the eye.
17. Light always passes straight through a transparent material without changing direction.
18. When an object is viewed through a transparent solid or liquid material the object is seen exactly where it is located.
19. Students will often think about how a lens forms an image of a self-luminous object in the following way. They envision that a "potential image" which carries information about the object leaves the self-luminous object and travels through the space to the lens. When passing through the lens, the "potential image" is turned upside down and may be changed in size.
20. When sketching a diagram to show how a lens forms an image of an object, only those light rays are drawn which leave the object in straight parallel lines.
21. Blocking part of the lens surface would block the corresponding part of the image.
22. The purpose of the screen is to capture the image so that it can be seen. The screen is necessary for the image to be formed. Without a screen there is no image.
23. An image can be seen on the screen regardless of where the screen is placed relative to the lens. To see a larger image on the screen, the screen should be moved further back.
24. The size of the image depends on the size (diameter) of the lens.
25. When two pulses, travelling in opposite directions along a spring or rope meet, they bounce off each other and go back in the opposite direction.
26. Colors appearing in soap films are the same colors that appear in a rainbow.