Ever wonder why surfers wear wetsuits even on a warm day at the beach? Water conducts heat away from the body. Rubber wetsuits, however, insulate the body to keep the cold of the ocean water away and hold body heat where it belongs — in the body.

Grab your board and catch the next wave with us as we learn more about thermal conductors.

Have you ever wondered…

• What does a thermal  conductor do?
• How does a thermos keep hot stuff hot and cold stuff cold?
• What does an insulator do?

Did you know?

You are probably more familiar with conductors than you realize. If you have ever poured a cup of tea, worn an oven mitt or taken a sip from a thermos, you already have some firsthand experience with thermal conductors.

Heat likes to travel, but only in one direction. Did you know heat travels only from warm or hot things to colder things? This makes sense when you realize there is no such thing as “cold.” There is only heat. Cold is simply the absence of heat!

If you hold an ice cube in your bare hand, it might seem like the coldness of the ice cube makes your hand cold. The truth, though, is that your hand is actually warming up the ice cube, as heat travels from your warm body to the cold ice.

The result? A melting cube. As your hand loses heat to the ice cube, it feels cooler.

Energy, such as heat, transfers through some materials easily. These materials are called conductors. Metals are great conductors because energy passes through them quickly.

Then there are materials called “insulators” that do not allow energy to pass through easily. These materials include plastic, cork, wood, Styrofoam and rubber. Thermal insulators are thus good at maintaining a consistent level of heat — whether hot or cold.

One example of a great insulator is a thermos. If you put soup in a thermos, you can open it later and enjoy warm soup on a cold winter day. The thermos insulates the soup, trapping the heat inside.

Likewise, if you are playing soccer on a hot August afternoon, your thermos full of ice water stays refreshing and cold. The thermos acts as an insulator, keeping heat out.

As you may have guessed by now, insulators make poor conductors. Manufacturers use this scientific fact to make products we use safer.

Consider the teapot, for example. If you have ever looked closely at a teapot, you may have noticed the body of the teapot is made of metal, while the handle is made of wood or plastic.

The body of the teapot must be able to conduct heat in order for the water inside to boil. Since metal is a great conductor, it easily passes heat from the stove to the water inside. That’s why manufacturers use metal for the body of the teapot.

You already know it would be a very bad idea to touch the body of the teapot with your bare hand. Thankfully, it has a handle. If the handle of the teapot was metal, however, it would also conduct heat from the stove — to your hand — and that would be a very unpleasant surprise.

In order to prevent burns, manufacturers make handles out of good insulators, such as wood and plastic. This means you can enjoy a warm drink without burning your hand.

Try it out!

Are you ready to become a mad scientist? Grab mom or dad and head to the laboratory, also known as the kitchen. You’ll need some help with this experiment because it involves hot water. Be careful!

Fill a bowl with hot water (the water does not need to be boiling). Once the bowl is full, experiment by partially submerging different objects in the water to see if they are good or bad thermal conductors. Try a metal spoon, a plastic straw, a wooden spoon and a pencil.

If the item is a good thermal conductor, you will feel heat begin to move through the object to your hand. If the object is a poor thermal conductor, you will notice no change.

Which objects make good thermal conductors? Which are poor thermal conductors?

Wonder words to know and use:

• surfer
• wetsuit
• conductor
• insulator
• thermal
• thermos
• travel
• cork
• Styrofoam

Still wondering?

Whether you’re “hot stuff” or “too cool for school,” you’re sure to enjoy exploring the effects of heating and cooling on the dispersal of food coloring in water. Visit Science NetLinks to explore its Hot and Cold Colors lesson!

Wonder what’s next?

Tomorrow we’ll meet a little guy in outer space who was demoted through no fault of his own. Get ready to say hello to our little friend.

• Tags: conductor, insulator, thermal