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

  1. Place a candle on a fire-safe surface.
  2. Light the candle and let it burn steadily for a short time.
  3. Blow out the candle, producing a visible stream of smoke.
  4. Immediately hold a lit match or lighter in the path of the smoke, a few centimeters above the wick.
  5. Observe the flame traveling through the smoke back to the wick, relighting the candle.

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.)