Internet Version [Naruhodo no Mori] Vol. 16

by Yumiko Mori

---

Vol. 16     March 15th, 1996

Surprising Experiments using a Microwave Machine

Home science experiments for mothers of elementary school children

Zzzzzzzz!!
Toshi: "Amazing! It sounded like thunder!"
Mom: "I am shocked. I thought the microwave was going to explode."
Toshi: "The edge of the foil is melting. It's amazing! Let's do it again."
Mom: "Again? I hope you will not break the microwave, Toshi!"

We have to have brave mind when we place a fluorescent light tube into the microwave machine and turn its switch on.
The microwave did not break. Mom is so pleased.
Next, we put ice cubes into a cup and microwave them.

Mom: "It's true! Ice doesn't melt! It's really strange, because water is extremely hot on the other hand.
Toshi: "Mom, what did you find?"
Mom: "I found ice did not melt. It's strange because frozen beef can be defrosted by microwave."
Toshi: "I guess what happened is heated beef melted ice around it."
Mom: "You sounds clever! Anyhow, it's so surprising to find ice does not melt in the microwave. "

Materials

1. A microwave machine

2. A steel wire pad (one without soap)
   A dish plate (one you can waste, since it may get dirty)
   Aluminum foil (cut out just 1 cm from the end)
   A water-filled cup
   (This water provides safety for your microwave. Needs to be kept in the microwave during experiments.)

3. A circular fluorescent light tube

4. Several ice cubes
   2 identical cups

Methods

1. Metal experiments
   
   • Cut a steel wire pad into small pieces (about size of a finger nail)

   • Place pieces of steel wire on a dish plate in a microwave. Microwave these for 20 sec.

   • Cut out aluminum foil by 1 cm in width and 5 cm in length.

   • Flatten the foil piece. Then fold the foil piece at the center line to make 'V' shape.

   • You may microwave both steel and aluminum foil at the same time.

   
   
2. Microwave a fluorescent light tube
   
   • Place a fluorescent light tube in a microwave machine, close it s door and start the machine.
     Switch off after the tube lights up.

   
   
3. Microwave Ice
   
   • Put ice cubes in a cup.
     (The cup should be completely dry. Otherwise this experiment would not work.)

   • In the other cup you put equal amount of water as ice.

   • Place both cups in a microwave and switch it on.

* Microwave was used for radar during the W.W.II.
These electromagnetic waves can stimulate water molecules. Thus microwaves can heat up food containing more water efficiently.

* Do not continue the experiments #1 or #2 more than 1 min in total, because these experiments may cause damage to microwave machines.

* Metal materials can reflect microwaves, but when microwave hits pointed parts of metal, free electrons move very rapidly and heat is produced.
The reason why metal mesh is attached on a microwave window is to prevent microwave from leaking out.

* In a fluorescent light tube, moving electron collides to electron of mercury atom, emitting photon, which subsequently hits the tube wall and make fluorescent light.

* Ice is a solid material made of water molecules. Because its firm arrangement of molecules, microwave can not stimulate the vibration of the water molecules.

   My children loved the sparkles we made in the microwave. On the other hand, I was most amazed by a fact that ice did not melt in the microwave. Why can we defrost frozen beef but not ice? I was so curious, that I investigated about ice. I learned the properties of ice are quite complicated. When you leaned one thing, you want to ask further questions. I don't think I myself can understand these difficult problems. But scientists are pursuing unsolved problems further and further.

---