demonstrations:convection_among_friends

Convection Among Friends

Materials: ★☆☆ Easy to get from supermarket or hardware store
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★☆☆ Minimal safety procedures required

Categories: Heat

Alternative titles: Heat Transfer with Hands, Convection and Conduction Demonstration

Summary

This interactive activity uses hand placement between partners to demonstrate convection, showing how heat transfers from warmer to cooler areas through moving air. It also introduces conduction when the partners’ hands touch directly.

Procedure

  1. Ask students to form pairs.
  2. One partner holds their hands palm-up.
  3. The other partner places their hands palm-down above the first partner’s hands.
  4. Partners slowly move their hands closer together and then farther apart, noticing the temperature differences.
  5. If no difference is felt, have one partner rub their hands together briskly to warm them before repeating the activity.
  6. Point out how heat feels stronger as the hands get closer, illustrating convection.
  7. To extend, have the partners briefly touch hands to demonstrate conduction.

📄 CONVECTION AMONG FRIENDS - Alan Nall: https://www.unco.edu/nhs/science/pdf/demos/1998_CSC.docx

Variations

  • Try having one partner heat their hands under warm water or with friction before starting.
  • Test with different distances between hands and note when heat is first felt.
  • Compare results indoors versus outdoors or in front of a fan to explore the role of moving air.

Safety Precautions

  • Avoid prolonged vigorous rubbing if hands are sensitive to friction.
  • Do not use external heat sources (like stoves or heaters) for warming hands—stick to safe methods like friction or warm water.

Questions to Consider

  • Why does the partner feel warmth without touching? (Heat is transferred by convection through moving air between the hands.)
  • What happens when hands touch directly? (Conduction transfers heat through direct contact.)
  • Why does rubbing hands increase the effect? (It generates extra heat through friction, making convection easier to notice.)
  • How is convection different from conduction? (Convection moves heat through fluids like air or water, while conduction transfers heat through direct contact between solids.)