Page 169 - Science Coursebook

11.4 Conduction of heat

Conductors and insulators
Metals such as copper, aluminium and steel are good
thermal conductors. Most non-metals such as wood hot end cold end
and plastic are poor thermal conductors. A poor thermal
conductor is called a thermal insulator.

The picture shows how energy conducts through solids.
At the hot end, the particles are vibrating a lot because
they have a lot of energy. They bump into their
neighbours, giving them some of their energy. Then
these atoms vibrate more and give some energy to their
neighbours, and so on. In this way, energy travels through In a solid, the particles vibrate more
the solid from the hot end to the cold end. at the hot end than the cold end.

Questions
A+I 2 Hot drinks are often served in plastic (Styrofoam) cups. Why are these easier
to hold than a paper cup?
A+I 3 Suggest two reasons why cooking pots are made of metal, not plastic.

Activity 11.4B
Melting ice

In this activity, you will have two blocks, one made of metal
and the other of plastic.
An ice cube is placed on each block. Which will melt first?

Before you carry out the experiment, think about
these questions:
• Why will the ice melt?
• How can energy get into the ice?
plastic block metal block
Explain your thoughts. Write a description of what you
observe, together with an explanation.

Summary
• Energy can be conducted through a solid or liquid from a hotter
place to a cooler place.
• When energy is conducted through a material, the material itself does
not move.
• In conduction, energy is transferred from one vibrating particle to
the next.

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