Academic journal article Science and Children

Conduction & Convection

Academic journal article Science and Children

Conduction & Convection

Article excerpt

1. Fill a test tube V5 full of crushed ice. Use your pencil to push in a little steel wool to hold the ice firmly in place.

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2. Now fill the test tube with water. The ice should stay the bottom.

3. Try to boil water at the top of the tube without melting the ice at the bottom.

[ILLUSTRATION OMITTED]

4. Repeat this experiment without steel wool. Let the ice float as you heat from the bottom.

[ILLUSTRATION OMITTED]

5. Is water a good conductor of heat? A good convector?

OBJECTIVE

To appreciate that water is a good convector of heat, but a poor conductor.

LAB NOTES

Use only as a demonstration for younger students.

INTRODUCTION

Heat travels by conduction, convection and radiation:

Conduction: Heat causes atoms and molecules to vibrate more energetically. These in turn agitate nearby particles, transferring thermal motion through the material. Conduction happens more rapidly with metals than with non-metals, because free outer electrons in metals collide and transfer their thermal motion more quickly.

Convection: Atoms and molecules in a fluid (liquid or gas) move more energetically as they absorb heat, thereby expanding and rising above cooler, denser layers of the fluid, that then sink as they are displaced.

Radiation: Radiant heat energy travels through space as a wave, partly electric and partly magnetic. …

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