Physics Dept. Demonstration Manual

DHT20 - Convection Currents, Air

Objective: Illustrates convection currents.


  • Glass container with two chimneys
  • Candle, Lab Jack
  • Braided string, matches


If a candle is lit under one chimney and a smoking string is held over the other chimney, the smoke will be drawn down the cold chimney by the warm air moving up the hot chimney.


Do not let the smoking string rest against the chimney walls, as the heat melts the plastic chimneys