Double Convex

How Does a Double Convex Lens Work?

 

Materials

• magnifying lens
• sheet of white paper

Try This

1. Darken all the windows in the room except the one at which you are working.
2. Hold the magnifying lens in your right hand.
3. Position the lens so it focuses on an object outside.
4. Hold the sheet of white paper in your left hand.
5. Move the paper slowly toward the lens until you see the outside object on the paper. What do you notice about the image?

What's Going On?

The image on the sheet of paper was upside down. The magnifying lens is thicker in the middle than at the edges. This double convex lens caused the light rays that were approaching from different directions to meet at one point called the focal point. The light rays then continued past the focal point and crossed each other. By the time the light rays reached the paper, they were reversed. The rays that came from the bottom of the object were at the top, and those that came from the top of the object were at the bottom. To see an object right-side up through a magnifying lens, the object you are looking at must be closer to the lens than the focal point.