how does a microwave heat food?

A microwave oven heats food by using electromagnetic waves to excite the molecules within it. Here is the step-by-step process:

1. Generation: The oven contains a component called a magnetron, which converts electricity into high-frequency radio waves, specifically microwaves.
2. Distribution: These waves are directed into the metal interior of the oven. The metal walls reflect the waves, causing them to bounce around and pass through the food.
3. Excitation: Most foods contain water molecules, which are "polar"—meaning they have a positive end and a negative end. As the microwave energy passes through, these water molecules frantically rotate back and forth to align themselves with the rapidly changing electric field of the waves.
4. Heat: This rapid rotation creates friction between the molecules. That friction generates thermal energy (heat), which then spreads to the rest of the food through conduction, cooking it from the inside out to varying degrees.

Because microwaves target water molecules specifically, foods with higher water content heat up much faster than drier materials.