How Microwaves Heat Food

A microwave oven heats food without flames or hot coils. It uses invisible waves of energy called microwaves. These waves make water molecules in food vibrate very fast. The vibrating molecules rub against each other and create heat. That is how your food gets hot in just minutes.

How Microwaves Work

Inside a microwave oven, a device called a magnetron produces microwave energy. The microwaves bounce around inside the metal walls of the oven. When they hit food, they are absorbed by water, fat, and sugar molecules. These molecules vibrate billions of times per second. The friction from all that vibration creates heat.

Why Some Things Heat Unevenly

Microwaves do not heat all parts of food at the same rate. Thick parts take longer than thin parts. The outside heats before the inside. That is why microwave instructions often tell you to stir food or let it stand. The standing time lets heat spread evenly through the food.

Fun Facts

• Metal should never go in a microwave because it reflects the waves and can cause sparks.
• Microwaves heat food from the outside in, not from the inside out as many people believe.
• The microwave oven was invented by accident in 1945 when a scientist's chocolate bar melted near radar equipment.

Did You Know?

Microwave ovens do not actually cook food with heat the same way a regular oven does. They make the food heat itself by vibrating its own molecules. That is why food in a microwave does not brown or get crispy!