Description: This demo projects the filament of a light bulb onto the screen using a Plano convex lens.
- Large convex lens
- Light bulb
- Jack stand
- VariAC to banana plug cable
- (Optional) A second large convex lens
- (Optional) Cardboard apertures and cardboard square
- Place the jack stand inside the box. The box is used to shield students from the bright light.
- Connect the VariAC to the light bulb.
- Place the light on the jack stand.
- Set the VariAC to 120V
- Align the lens in front of the bulb. Focus the image on a screen or wall at the other side of the room. Slight adjustments to the lens may be needed to get a good image.
- Turn on the VariAC.
- Turn off the room lights.
- Note the projected image of the light bulb filament.
- Use 2 large Plano convex lenses instead of one. Focus the image on the screen again.
- Using the cardboard apertures, you can show what happens when you limit the amount of light through the lens with different apertures.
- Using a cardboard square, block the bottom half of the outer lens. Note that the full image is still present. Repeat with blocking the top half of the outer lens.