The metal walls and sometimes doors are a safety precaution to keep microwaves from cooking things outside. The outer metal reflects the microwaves toward the food. A fork for example in food when heating conducts a lot of electricity, so it can create problems, but in theory if you have enough substances in the microwave to absorb the waves (food, water, non conductive material) then nothing will happen.
How To Use A Microwave (For Dummies)
Step 1: Ensure microwave is plugged into a working socket
Step 2: Open microwave door
Step 3: Ensure there are no Mexicans hiding in the microwave. They are trying ever-more desperate ways to cross the border
Step 4: If there are no Mexicans hiding in the microwave, insert foot
Step 5: If there are Mexicans hiding in the microwave, insert foot into each Mexican until there are no Mexicans hiding in the microwave
Step 6: Turn microwave on to full power for at least 3 hours
Step 7: Pull out foot. By now it will be fully black. You may notice beneficial results such as being able to jump higher, but side-effects do include being shot at by police and not knowing who your father is
As food gets hot, water just converts into steam and the energy gets released. As the molecules inside a piece of aluminum foil heat up, they don't have anywhere to go. The metal heats up very rapidly and will eventually catch on fire. The metal walls dont do this because the are completely flat and the reflect the microwaves
The metal forks and stuff are made up off are conductive metal that react with the rays used to heat up food. My guess is that the lining of the inside is a weak reactive metal. (idk which one im 10)
Step 1: Ensure microwave is plugged into a working socket
Step 2: Open microwave door
Step 3: Ensure there are no Mexicans hiding in the microwave. They are trying ever-more desperate ways to cross the border
Step 4: If there are no Mexicans hiding in the microwave, insert foot
Step 5: If there are Mexicans hiding in the microwave, insert foot into each Mexican until there are no Mexicans hiding in the microwave
Step 6: Turn microwave on to full power for at least 3 hours
Step 7: Pull out foot. By now it will be fully black. You may notice beneficial results such as being able to jump higher, but side-effects do include being shot at by police and not knowing who your father is