Question

How will you show experimentally that metals are good conductors of heat?

Answer 1

Hint: Conductivity of metals is due to excitation of freely moving delocalised electrons on applying electric voltage. As we know like charges repel each other, the movement of one free electron gets repelled by those of the nearby atom, moving in the direction of current towards the positive end.

Complete step-by-step solution:
Metals are those substances which are characterised by the conduction of heat and electricity. The reason behind this is atoms inside a metal quickly lose electrons on supplying energy and make positive ions called cations.
Metals are very strong, durable and shiny substances used for making automobiles, cooking utensils, satellites, etc. few other properties of metals are they are malleable (can be beaten into thin sheets), ductile(can be drawn into wires) and sonorous.
The materials which tend to be a good conductor have freely moving electrons in excess. To prove that metals are good conductors of heat, we can perform an experiment.
Let us take a knife with a heat resistant handle and put it on flame for two minutes till it's warm enough. Put the knife on butter and look at the melting process. The butter starts melting and this shows that metal is a good conductor of heat.
Let us take another example. Take an iron rod and put its one end on fire for a few minutes. You’ll notice that slowly heat will reach the other end, which will warm the iron rod completely.
You can relate with many day-to-day activities and notice the same phenomenon. These examples justify that the free electrons in the metal get excited on supplying energy and produce heat or electricity. Hence, metals are good conductors of heat.

Note: Semiconductor metals do not conduct electricity or heat despite having high numbers of valence electrons. But when they are heated or doped with silicon and germanium, they become efficient conductors of electricity.