why can't you put metal in the microwave?

Answer 1

technically, temperature can be discribed as kinetic energy of the molecule, the faster the molecule moves, the higher its temperature. microwave causes dielectric heating, it can only heats insulator, anything that does not conduct electricity. It heats up insulator by causing friction at molecular level.

Molecular rotation occurs in materials containing polar molecules having an electrical dipole moment, which will align themselves in the field by rotating in place; as the field alternates the molecules reverse direction, and the successive rotations causes heat through friction at the molecular level.

As we know, metals are conductors, good conductors in fact. if we apply microwave radiation to it, we wont be heating it but create current. Any object containing pointed metal can create an electric arc (cause sparks) when microwaved. Forks are a good example. This is because the tines of the fork resonate with the microwave radiation and produce high voltage at the tips. This has the effect of exceeding the dielectric breakdown of air, about 3 megavolts per meter (3×106V/m). The air forms a conductive plasma, which is visible as a spark. Because now the air becomes a conductor, yes, a conductor just like copper wire, it will cause a shortage and burn your microwave. And any time dielectric breakdown occurs in air, some ozone and nitrogen oxides are formed, both of which are toxic, but it's less significant compared to the plasma and fire you got.

Answer 2

You can put metal in a microwave, with some limitations; some cooking instructions even recommend covering parts of food with aluminum foil to slow heating in one spot.
Limitations:
1. There must be something in the oven, such as a fair-sized portion of food or water, to absorb the power.
2. The metal must be fairly small compared to the food and the wavelength of microwaves (a few cm).
If there is insufficient food, or the metal is too large, or in the wrong part of the oven, it cause "standing waves" where the voltage and current are out of phase; in that case, the voltage may be high enough for sparks in the oven (obvious) and breakdown in the magnetron (not easy to see), which can cause damage.

Answer 3

Because a microwave doesn't heat food the same way that fire does. A microwave excites the molecules and makes them move very fast. The fast motion causes friction, which in turn causes heat. The molecules in metal are placed too closely together. That is why metal often sparks when you turn on the microwave. The molecules collide instead of causing friction.

Answer 4

The walls of a microwave oven are made of metal so any other metal object can cause sparks to jump between itself and the metal oven walls, damaging the oven or even starting a fire!

Answer 5

you can. but just don't turn it on.