Microwaves are designed to heat up food efficiently and quickly, but they are not intended to heat up everything around them. When you use a microwave oven properly, the microwaves should primarily interact with and heat the water molecules in your food. This is because water molecules in food are polar, meaning they have a positive and negative end, which makes them more susceptible to the microwave's electromagnetic radiation.
However, there can be some minor effects on other nearby objects, such as the kitchen countertop or tabletop. Microwaves can interact with some materials, especially those containing water molecules, like certain types of ceramics and glass. If these materials are within close proximity to the microwave oven while it's running, they may absorb some microwave energy and heat up slightly. This can be more noticeable if the microwave is used for extended periods or if the nearby objects are particularly sensitive to microwave radiation.
For this reason, it's generally a good idea to leave some space around the microwave oven while it's operating, especially if you notice any heating of nearby objects. Additionally, using microwave-safe containers and avoiding metal or materials that are not microwave-friendly can help minimize any unwanted effects.
In summary, microwaves primarily heat up the food inside the oven by interacting with its water molecules, but some minor heating of nearby objects can occur depending on the materials and their proximity to the microwave. Proper usage and safety precautions can help mitigate any potential issues.