PURPOSE (Step 1):

• I wanted to find out how microwave ovens heat up food?

RESEARCH (Step 2): • The microwave was accidently discovered by Percy

Spencer. He was an engineer who worked for Raytheon in 1945.

• He found that when microwave energy (or radio waves) hits a high frequency it would create heat. Radio waves are absorbed by water, sugar and fat molecules. When the sugar, fat and/or water molecules are hit by the radio waves they are converted into atomic motion, or heat. The radio waves make the molecules jiggle and move and spin. The faster they spin the hotter they get. When things heat up, they expand.

HYPOTHESIS (Step 3):

• If microwaves hit cold food containing molecules of fat, sugar or water then the food should get hot and if it gets hot then it should expand. If there are not fat, sugar or water molecules in the item of food it should not get hot or expand.

EXPERIMENT (Step 4): Exploding Marshmallows

• Marshmallows have fat, sugar, and water molecules in them. Soap does not. If we put the marshmallows into the microwave oven, the radio waves will cause the marshmallows to get hot and expand. If we put the soap in the microwave oven it should not get hot and expand.

What I needed:

• Marshmallows• Paper plate• Microwave oven• Bar of soap (control)

What you do:

• Place a marshmallow on a plate in a microwave. Turn the microwave on high for 30 seconds. Watch what happens.

• Change the time you microwave the marshmallow and see what happens.

• Repeat this experiment with a bar of soap. See what happens.

OBSERVATION AND ANALYSIS: • When we put the marshmallows in the microwave oven on a

paper plate and turned it on for 30 seconds, we watched through the glass window of the oven and the marshmallows got three times their normal size. When we opened the door to the microwave oven the marshmallows immediately lost all their big size and went flat but they were very hot. The paper plate was not hot. When the marshmallows cooled, they were not fluffy anymore. They got hard.

• Then we put the bar of soap on a paper plate and placed it in the oven. We set the time for 30 seconds and again watched through the window of the oven. The soap did not move or change in anyway. It was not hot to the touch when we got it out.

Marshmallows before Microwaving

Marshmallows after microwaving for 10 seconds

Marshmallows in microwave after 20 seconds

Marshmallows after microwaving for 30 seconds

Marshmallows after removed from Microwave

CONCLUSION (Step 5):

• My conclusion is that my hypothesis was correct. The things with water, fat and/or sugar did get hot and expand but the soap did not because it did not have any of those things in it. If I could change my experiment in any way I would try it with a lot of different kinds of foods. I would like to know how other foods would change and see it they had sugar, water and/or fat in them and how they would change if microwaves hit them.