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.)