No, if a microwave is turned off and the door is closed, it will not generate any microwaves and therefore will not heat up. The microwave oven generates microwaves only when it is actively operating and the door is closed properly.
Microwave ovens work by using electromagnetic waves, specifically microwaves, to generate heat in the food or liquids placed inside. These microwaves are produced by a device called a magnetron, which converts electrical energy into microwave radiation. When the oven is turned off, the magnetron stops producing microwaves, and the heating process ceases.
It's important to note that microwave ovens are designed with safety features to prevent the emission of microwaves when the door is open or not properly closed. These safety mechanisms ensure that microwaves are contained within the oven during operation and do not pose a risk to users.