Burning Paper with a Convex Lens

A convex lens is used to concentrate sunlight onto a small point on a piece of paper. The focused light intensifies the heat at the focal point until the paper ignites.

1. Put on sunglasses for eye protection (Note: do not look at sun directly or through convex lens).
2. Take the experiment outdoors on a sunny day.
3. Place a sheet of paper on a flat, safe surface.
4. Hold the convex lens above the paper so sunlight passes through it.
5. Adjust the distance between the lens and paper until the light forms the smallest, brightest spot possible.
6. Keep the focal point steady on the paper until it begins to smolder and burn.
7. Extinguish the fire once the demonstration is complete.

CONVEX LENS AS BURNING GLASS - Make Me Scientific:

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• Try using different colors or thicknesses of paper (darker paper burns more easily).
• Experiment with different sizes or curvatures of convex lenses.
• Test if artificial light sources (like a strong lamp) can focus enough energy to burn paper.

• Perform only outdoors in a clear area, away from flammable materials.
• Wear sunglasses to protect your eyes from bright concentrated light.
• Always supervise children during this activity.
• Extinguish any flames immediately after the demonstration.

• Why does the convex lens make sunlight more intense? (Because it focuses parallel rays of sunlight to a single point, concentrating the energy.)
• Why does darker paper burn more easily than white paper? (Dark paper absorbs more light energy, converting it to heat faster.)
• Could ordinary flat glass burn paper the same way? (No, because it does not converge light to a focal point like a convex lens does.)