G4_Air is to Insulator as Copper is to Conductor_830L_01

There is nothing better than hot soup on a cold day. Yum! This new thermos works great at keeping Mom’s homemade soup hot. Have you ever wondered how you can hold the outside of the thermos and not get burned by the hot contents? Let’s look at a more common occurrence. If there is a hot object and you are close to it but do not touch it, why don’t you get burned? This probably sounds like a silly question. The answer to this question ties directly to an understanding of an insulator.

It is of course the air that is separating you from the hot item. This is an important concept that distinguishes many insulators from conductors. Consider what would happen if you were connected by a long thin piece of copper to the hot item. What do you think would happen? Correct! Eventually, the copper would conduct the heat to you. So we can agree that air is a good insulator, but why?

All solids, liquids, and gases are made up of particles called molecules. Air is a good insulator because its molecules, like any gas, are far apart. This minimizes the contact between them. By reducing the contact, it limits the transfer of energy between the molecules.

What is the most common way to not burn yourself? By not coming into contact with hot items, correct? Duh! One of the best ways to do that is to have air between you and the item. Is there an even better way?

So what could be better than air as an insulator? How about having no air molecules? Is that even possible? Yes. If it is the transfer of energy from colliding molecules that is the cause of heat transfer, then the best insulator would have no air molecules (a vacuum).