why is it dangerous to put metal objects in a microwave oven?

Answer 1

"Any metal or conductive object placed into the microwave will act as an antenna to some degree, resulting in an electric current. This causes the object to act as a heating element. This effect varies with the object's shape and composition.

Any object containing pointed metal can create an electric arc (cause sparks) when microwaved. This includes cutlery, aluminium foil, ceramics decorated with metal, and most anything containing any type of metal. 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. The plasma and the tines may then form a conductive loop, which may be a more effective antenna, resulting in a longer lived spark. Any time dielectric breakdown occurs in air, some ozone and nitrogen oxides are formed, both of which are toxic.

The effect can be seen clearly on a CD or DVD. The electric current heats the metal film, melting the plastic in the disc and leaving a visible pattern of concentric and radial scars. It can also be illustrated by placing a radiometer inside the cooking chamber, creating plasma inside the vacuum chamber.

Microwaving food containing an individual smooth metal object without pointed ends (for example, a spoon) usually does not produce sparking. The formation of sparks on sharp metal objects may be prevented by placing the utensil in a conductor such as water, as charge cannot build up within a conductor. Altering the electrical properties of the food may, however, change how it is cooked, for better or worse.

Several microwave fires have been noted where Chinese takeout boxes with a metal handle are microwaved. Twist ties containing metal wire and paper are also notoriously dangerous. Common sense is to be careful, and not to leave the microwave unattended when heating anything unfamiliar. If a spark is observed, immediately open the door to cut the power. This will not let microwaves out, or anything else harmful.

Another hazard is the resonance of the magnetron tube itself. If the microwave is run without an object to absorb the radiation, a standing wave will form. The energy is reflected back and forth between the tube and the cooking chamber. This may cause the tube to cook itself and burn out. Thus dehydrated food, or food wrapped in metal which does not arc, is problematic without being an obvious fire hazard.

Certain foods if carefully arranged can also produce arcing, such as grapes. A naked flame, being made of conductive plasma, will do the same."

Answer 2

Yes. Some of the microwave rays reflect off the metal back at the microwave, damaging the microwave.

It could cause the microwave to malfunction, and worst case scenario, explode.

Answer 3

Metal objects in the microwave get insanely hot and can cause sparks or break the main parts of the microwave. Foil especially will do this.

Answer 4

Metal objects absorb immense amounts of microwave radiation and turn the radiation into short-circuit current.

Foil-paper fast-food wraps can ignite, and the short-circuit can even influence the load on the magnetron in the microwave, destroying the appliance.

For such a question, you are aptly named.

Answer 5

Well you see, microwaves product energy or radiation waves. If the waves hit the metal and get it hot. It cause electricity.

Answer 6

metal (especially aluminum foil) may bounce off microwaves.. i don't think it's gonna get hot..foods get cooked in microwave ovens because they have moisture and they absorb the waves.....maybe micowaves bounced off by metal would damage the oven itself

Answer 7

Years ago, my friend put a chicken wrapped in tin foil in the microwave by mistake...........it blew the door off the microwave!!!!

Answer 8

Depending on the size of the object, your microwave can catch on fire.

Answer 9

My new microwave recommends using flat aluminum foil strips to shield portions of certain meats while cooking.
i.e. exposed bones, narrow or irregularly shaped cuts, chicken wings, fish tails, etc.

Answer 10

true story : i came home from the pub..put on a 60 second burger .....i must have put it on 60 mins..iwas awakened by my daughter shouting the pc was on fire, but it was the microwave .1 melted door......ps i would have thought the fuse should have blown