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Test yourself
1 Which materials make the best conductors of heat?
2 What is an insulator? Name three insulators.
3 Explain how heat is conducted along a metal bar.
4 Suggest why
a) the base of a saucepan is made of metal.
b) the handle of a saucepan is made of plastic.
c) polar bears have a thick coat of fur.
d) birds fluff out their feathers in winter.
Answers
Explanation:
1. Copper is a good conductor of heat.
2.Insulators are used to protect us from the dangerous effects of electricity flowing through conductors.Name of insulators:-glass, plastic, rubber, air, and wood.
3.When something is heated, its atoms vibrate. If one end of a metal bar is heated, the atoms at that end vibrate more than the atoms at the cold end. The vibration spreads along the bar from atom to atom. The spread of heat in this way is called conduction
4.a.Metal pots are made from a narrow range of metals because pots and pans need to conduct heat well, but also need to be chemically unreactive so that they do not alter the flavor of the food. Most materials that are conductive enough to heat evenly are too reactive to use in food preparation
b.The handles of frying pans are made of plastic or insulating materials because plastic and insulating materials doesn't allow the heat to flow from pans to handles so that it will be easy to hold the frying pans.
c. the polar bear's coat has no white pigment; in fact, a polar bear's skin is black and its hairs are hollow. ... They have a thick layer of body fat, which keeps them warm while swimming, and a double-layered coat that insulates them from the cold Arctic air.
d. the coats people wear, birds tend to get puffier in winter. “A bird's body heat warms the air between its feathers,” Marra explains. “So birds fluff up in the cold to trap as much air in their feathers as possible.