Tuesday, January 6, 2009

Microwave Ovens

My dad remembers his first television. You might remember your first personal computer (Mine was a Comodore 64. It was cool.). But the thing that made me sure that all those science fiction books were coming true was our first microwave oven. No waiting hours for baked potatoes! For a while I tried to cook everything in the microwave. Dad bought me a cookbook and we had dinner ready in fifteen minutes flat almost every night for a while... um, I don't do that anymore.

But how did it work? Nobody could tell me. Not really. Why did some things cook faster? Why did frozen burritos have really hot spots and still frozen spots after their allotted two minutes? The answer lies in both the wave and the water: that is the microwave and water molecules.

First, lets look at a water molecule.

Okay, it's not really a water molecule. It's a drawing I made of a water molecule. H2O means that it has two hydrogen and one oxygen atom and they are sharing electrons. But they don't share them evenly. The oxygen atom hangs onto them more and this causes it to have a slight negative charge and the hydrogens to have a slight positive charge.

That charge is important in how the microwave affects it. The microwaves in a microwave oven oscillate back and forth with an electric and magnetic field that is at just the right wavelength to cause those water molecules to spin. Since heat is the energy of molecular movement and this spinning causes a great deal of movement, the water heats up fast.

The hot water in the food heats the rest of the food, so food with less water in it takes longer to get hot. What about the hot spots in the frozen food? Ice doesn't act like water. Those microwaves have a hard time affecting frozen water so the microwaves grab onto the spots that have started to thaw out already and those are the places that get hot first.

Posted by Marilyn at 1:00 AM
Labels: ,

7 comments:

  1. This blog would be so cool if that font wasn't so nerdy. :)

    JK. I love it.

    My first computer was a Comodore 64. I don't even remember if it did anything, other than play mindsweeper or some game like that.

    And also-I love the word oscillate.
    ReplyDelete
  2. I get the part about the frozen food not being able to heat evenly because of not having enough liquid.
    But why does thawed stuff (or stuff that wasn't frozen to begin with) not heat evenly either?

    For example, pour a jar of nacho cheese dip into a bowl. Microwave it on high for a few minutes.
    You'll notice that the center is lukewarm, whereas the edges are so hot they've started to bubble.
    Put it in for a few more minutes until the center is absolutely hot.
    The edges will be scorched.

    Why is that?

    P.S. My first computer was a Commodore VIC-20. I really wanted a 64 but never got one. Sad, I know.
    ReplyDelete
  3. Very cool blog you have here. :)


    - Kelly
    http://conventionfans.today.com
    ReplyDelete
  4. I like the way you explain scientific stuff. (I'm so technical, right?) Anyway, the scientific world has always fascinated me, but my brain just doesn't seem to be wired the right way to truly grasp it. I like that you can explain things in a way to the non-scientific peeps that we can understand.

    If you ever feel so inclined, maybe you could answer a science-y question I've had for a long time in a future blog. We all know the formula for water and we seem to have gobs of hydrogen and oxygen on the planet so how come we always have conserve water and worry about droughts? How come we can't just manufacture the water? (That might be a dumb question...my mind just always kept going back to that...)

    Jen
    http://darkpassenger.today.com
    ReplyDelete
  5. What amazes me is how a person comes up with the idea Microwave and wala it's done.. they are worth millions.. while see sit here going.. What was that, that just happened.. Know what I mean?
    ReplyDelete
  6. Mags: If you learned BASIC you could make a hot air balloon float across the screen. Also, you could play Zork, which was very important.

    Janna: I think that it has to do with the composition of the food, the container, and the way the microwaves bounce around in there. The edges of the cheese getting hot first like that might have to do with some metal or polar molecules in the container. Foods with an uneven water content get hot where there's more water first. Also, my microwave seems to have, "hot spots," where the microwaves must congregate or something. It isn't as noticeable now that microwaves all seem to have turntables but back when they started, you could really tell.

    Dreadpiraterose: I keep trying to comment on your blog but it eats my comments. I'll figure out what I'm doing wrong eventually. It has been happening on a lot of wordpress blogs lately.

    JNicole: I think that's a matter of energy, but I'll cover it next week some time. I keep a list of questions asked in comments that I need to cover in a post. And thank you for the compliment. That's what I'm aiming for and it's nice to know that I'm getting there.

    Callie Ann: Have you ever been sitting around BSing with friends about some cool idea and then two months later it is being advertised on TV? I hate that. I think engineers are just more action oriented than the rest of us. Also, they have business folks that listen to them, where I just have my family and they give me looks like I'm an alien or something.
    ReplyDelete
  7. Yes My first husband use to do that a lot.. sit around think about car junk a few months later. It is doing just what you said. being advertised. Your family looking at you like your an Alien.. they have no imagination..LOL
    ReplyDelete

Subscribe to: Post Comments (Atom)