Concepts

Image formation, convex lens

Overview

The image of a filament can be projected onto a wall. The filament can be blocked by an index card to show that the image is projected upside-down. The lens can be partially blocked by an index card to show this does not block parts of the image.

Details

Equipment

• [1] Light bulb in holder
• [2] Lab stand
• [2] 90-degree clamp
• [1] 3-finger clamp
• [1] Magnifying glass
• [1] Index card

Classroom Assembly

1. Mount the light bulb on a stand.
2. Mount the magnifying glass on the other stand.
3. Plug in the light bulb holder.
4. Turn on the light bulb and arrange the elements to project a filament image where desired.
5. Turn off the light bulb.

Script

1. Turn on the light bulb.
2. Ask students what will happen when you start blocking the light bulb from the bottom.
3. Block the bulb from the bottom, showing it blocks the image from the top, so the image is inverted. Block the bulb from the top for further emphasis, if desired.
4. Ask students what will happen when you start blocking the magnifying glass from the bottom.
5. Block the magnifying glass from the bottom, dimming the image.
6. Turn off the light bulb.

Additional Resources