Why does a microwave turntable rotate?
Short answer
A microwave turntable rotates so the food moves through different parts of the oven and heating becomes more even. Microwave energy is not distributed equally everywhere inside the oven cavity.
In 30 seconds
The metal walls of a microwave oven reflect microwaves. When reflected waves overlap, some places receive more microwave energy and others receive less. These hot and cold spots can make food heat unevenly. Rotating the food moves it through those positions, so it is less likely to stay in one spot for the whole cooking time.
Why does heating vary inside?
Microwave energy is absorbed by food and contributes to the motion of molecules, producing heat. But the waves inside the cavity reflect from the walls and overlap with one another. The food’s shape, amount, and position can therefore affect how much energy different parts receive. This is one reason microwave heating can be uneven.
What does the turntable change?
As the turntable moves the food, each part passes through different positions in the cavity. The food is less likely to remain for a long time in only a strong or only a weak part of the microwave pattern, so its overall heating can become more even.
A turntable does not make every part of the food exactly the same temperature. Thickness, shape, moisture, amount, and the container also affect heating.
Some microwaves do not use a turntable
Some models use another design, such as a component that changes the microwave distribution or a different heating control method, to reduce uneven heating. A microwave without a visible turntable can still heat food. Follow the instructions for the specific model.
Key point
Even with a turntable, stirring or rearranging food partway through heating, and allowing it to stand afterward, can help the temperature even out. When thorough heating matters, follow the package or appliance instructions and check that the center is hot enough.