Monday Leftovers: How a Microwave Oven Works

How a Microwave Oven Warms Your Food

1Every Sunday, the Mensah family cooks a big pot of peanut stew. On Monday night, nobody wants to cook again, so they reheat the leftovers in the microwave oven. In just a few minutes, a cold bowl of stew is steaming hot. How does a microwave oven warm food so quickly?

2A microwave oven does not have a flame or a glowing coil like a stove. Instead, it makes microwaves. Microwaves are waves of energy, a little like the radio waves that carry music to a radio. They are invisible, so you cannot watch them work. Inside the oven, the waves bounce off the metal walls and pass into the food.

3Most foods contain water. The microwaves make the tiny bits of water in the food jiggle back and forth very quickly. All that jiggling makes heat, and the heat warms the food.

4Microwave ovens often heat food unevenly. The edge of a bowl can be bubbling while the middle is still cold. That is why many microwave ovens have a turntable, a round glass plate that slowly spins the food. Stirring the food halfway through also helps spread the heat. A microwave oven usually does not need to be preheated, so you can start right away.

5Some things do not belong in a microwave oven. Metal objects, such as forks or crumpled foil, can make sparks. Some plastic containers can melt or bend out of shape. Before you use a dish, look for a label that says microwave-safe. Many glass bowls and ceramic plates are good choices.

6Finally, be careful when the timer beeps. Steam can build up under a lid, so lift it away from your face. Mr. Mensah always checks the stew with a food thermometer to make sure it is hot all the way through. Then everyone grabs a spoon. For the Mensah family, leftover night is the easiest dinner of the week.