Convection currents

What the Activity is for

The purpose of this activity is to provide a clear demonstration of convection currents.

What to Prepare

• a waxy paper straw to provide smoke
• matches
• a candle under one of a pair of linked chimneys

What Happens During this Activity

Place the apparatus in a favourable light, where it can be clearly seen. Make sure there is a plain white backdrop. Describe the apparatus, showing the linked pair of chimneys with the candle placed under one.

Ask what will happen to the air in the chimney with the candle when the candle is lit. Make sure you challenge any suggestions that heat rises. Then ask what will happen to the remainder of the air in the apparatus. Try to build a clear expectation of what will happen before carrying out the demonstration. Light the candle – no air movement is seen. Introduce the smoke as a tracer above the empty chimney by pouring it down the smouldering straw with the unlit end held just above the chimney, but lower than the lit end. The smoke will follow the air down this chimney and up the other one.