In a toaster, current is run through a piece of wire to produce heat.
1. If you hold your hand above the toaster it feels hotter than if you hold you hand beside the toaster. Why?
2. If you look inside the toaster when it is on you can see the hot wire glowing red. Compare the temperature of the wire to the temperature of the filament in a typical incandescent light bulb.
3. Why aren't toasters made with filaments that glow yellow?
4. When the toaster turns off, the wire quickly stops glowing red. Why does radiation cause the wire to cool off very quickly?
5. The outside surface of many toasters is shiny and mirror like. How does this help the toaster to be more efficient?
Many animals have developed special ways of insulating themselves.
6. Deer have hollow hair. How does this help insulate them?
7. Ducks have oily feathers. Not only does this help them float, but it also helps insulate them. If a duck had water trapped in the spaces between feathers it would cool off faster than if it had air trapped in these spaces. What difference between water and air would cause this?
8. A seal has a thick layer of fat under its skin. Why does a thick layer of fat help the seal to retain heat better than a thin layer?