Conduction

1. Good conductors are materials that allow heat to pass through them easily. All metals are good conductors. This is because metals contain free-moving particles called electrons. These electrons transfer energy from hotter parts to colder parts of the metal.
2. Bad conductors (also called insulators) are materials that do not allow heat to pass through easily. Examples include non-metals like wood and glass.

Examples of Conductors and Insulators:

1. Use carpets, curtains, and draught excluders to reduce heat loss at home.
2. Double glazing: Windows with two panes of glass and air in between reduce heat loss. Air is a poor conductor and slows down heat transfer.
3. Cavity wall insulation: A material is inserted between walls to prevent heat loss. It also reduces air movement, lowering convection as well.

To compare the heat conduction of different materials, Edser's apparatus can be used. The apparatus includes:

1. A copper can with identical rods made of aluminum, copper, lead, and iron fixed at the base.
2. The can is supported and clamped on a retort stand.
3. When hot water is poured inside the copper can, heat flows through the rods by conduction.

As time passes, wax placed on the rods melts. The distance the wax melts shows how well each rod conducts heat. The farther the wax melts, the better the conduction.

1. Most liquids (except mercury) and gases are poor conductors of heat.
2. Gases are even worse conductors than liquids.
3. Since liquids and gases are poor conductors, they mainly transfer heat using convection, not conduction.