A microwave is a must in the kitchen. It heats up food so easily and efficiently, but have you ever thought about the difference between an oven and a microwave? When the cooking is done and the door of the oven is opened, you feel the heat on your skin. So why doesn't the same thing happen when you open the microwave door? The answer is that an oven cooks food by convection while a microwave heats up food by radiation. Although both convection and radiation can occur in air, they are totally different heat transfer modes. Convection uses the circulation of heated air to heat up foods. Radiation uses electromagnetic (thermal) waves that penetrate your food and heat the molecules inside.
Here are the accompanying handout slides for this lesson.