Wednesday, December 19, 2007

Convection, Conduction, and, Radiation

Today, a student asked me a question about conduction, convection and radiation: "I am always confused between the difference of conduction, convection and radiation. What is being used in pouring hot water from a thermos?"

Students will often ask things that are assigned as homework. This might have been a homework question, or, it might have been genuine curiosity. I am always glad when students are curious.

I've taken the liberty of discussing the topic here because it is a topic on many state standards.

For these types of questions, try to guide a student in finding an answer. In this way, he or she is likely to remember the content learned. Here is a sample set of guiding questions and activities. I have also included some movies. Your students might be able to make movies that are more exciting and helpful to them. Review the "Botany Beat" or Tomato movies for some ideas. Here is one student's movie:

First, have you defined all the words? (You can use the dictionary links at the bottom of the page. Be sure to note down the date and the source you used.)

Conduction is ________________________________________________________
Here is a simulation on conduction:

And, here is an animation about conduction:

Convection is ________________________________________________________

Here is a movie on convection currents:

What do hot and cold have to do with convection?

Here's another convection movie showing some experiments and relating them to every day life.

Radiation is ________________________________________________________

Here is an animation on radiation and convection:

If you have trouble remembering them, try writing the definitions three or four times , or, try drawing a picture or writing a song about each one.

Also, try discussing these ideas with your friends or where you get snacks after school or with a mentor or adult in your family or community. These things can help you to remember them.

Did you brainstorm about them?

Do you have a thermos? If you don't have one, try to borrow one, otherwise, the question will be hard to answer.

If you put hot water in a thermos, can you feel the heat outside the thermos when you hold it?

What about if you put your hand over the thermos, can you feel heat, even when you are not touching anything?

What if you compare putting a plastic spoon into the hot water with putting a silver spoon into the hot water. What happens?

Think of things you know, for example:

The sun rays radiate.

The convection oven has heat rise and fall in circles.

A copper wire conducts electricity.

Now, think again about the question. When you pour hot water from a thermos, do you feel heat without touching it?

Does some heat stay in some matter, yet move?

Does some heat transfer from the hot water to the bowl or sink you are pouring it into?

Now that you have thought about all these things, and tried some of them, I think you can be confident of the answer that you develop. Be sure to back up the answer with why you picked it. You might speak, write and draw your answer, too. Let me know what you find out. Write back if you are still stuck. Dr. J

Related links:

Update... 2009
(c)2007, 2008, 2009 J. S. Shipman