Physics 2000 Einstein's Legacy Microwave Ovens

Overview

Click on "Top View" to put marshmallows into the microwave oven.


Curious why some marshmallows cook faster than others? First, hold the SHIFT key down and click on the tray to fill the whole tray at once and look at the pattern of "hot" and "cold" spots. Then read about Hot Spots for an explanation.

Dr. Lee, how is it that the marshmallows cook without the tray or the air getting hot? That's not how a regular oven works.

That's a good observation, Alex. Here's why -- microwave ovens selectively make liquid water hot. Most food, even "dry" foods, have water in them.

So only the food gets warm?

Yes and no. Other things can get hot by being in physical contact with the hot food.

You haven't said why the water gets hot. What's special about water?

The microwave oven generates electromagnetic waves (called microwaves) which makes water move. This motion leads to friction, and friction leads to heating.

Motion
Friction
Heating



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