demonstrations:traveling_flame
Travelling Flame
Materials: ★☆☆ Easy to get from supermarket or hardware store
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★★☆ Some safety precautions required to perform safely
Categories: Combustion
Alternative titles: Relighting a Candle with Smoke, Candle Smoke Ignition
Summary
When a candle is blown out, the rising smoke contains vaporized wax. Bringing a flame into the smoke can ignite the vapor, causing the flame to travel down the smoke trail and relight the candle wick.
Procedure
- Place a candle on a fire-safe surface.
- Light the candle and let it burn steadily for a short time.
- Blow out the candle, producing a visible stream of smoke.
- Immediately hold a lit match or lighter in the path of the smoke, a few centimeters above the wick.
- Observe the flame traveling through the smoke back to the wick, relighting the candle.
Links
Magic Traveling Flame - Relight a Candle Using Its Smoke - The Sci Guys:
Traveling Flame: a fun at-home science experiment - Science Beyond:
📄 Traveling flame - Experiment Archive: https://www.experimentarchive.com/experiments/traveling-flame/
Variations
- Test how far away the flame can be held from the wick and still relight the candle.
- Experiment with blowing the candle out at different angles to see how the smoke trail changes.
Safety Precautions
- Keep a fire extinguisher nearby.
- Perform the demonstration on a fireproof surface away from flammable objects.
- Do not leave the lit candle unattended.
- Extinguish matches and lighters safely after use.
Questions to Consider
- What is in the smoke that allows the flame to travel back to the wick? (Unburned, vaporized paraffin wax that can still ignite.)
- Why does the candle stay lit once the flame returns to the wick? (The wick draws up liquid wax, which evaporates and burns continuously.)
- Why does blowing on a candle put it out? (It disperses the hot vapor and flame, stopping fuel from reaching ignition temperature.)
- How is this demonstration an example of incomplete combustion? (Not all the wax burns when the flame is extinguished, leaving vaporized wax in the air.)