Why does food catch fire in the microwave - no metal!?

Question

Whenever I microwave broccoli, macaroni&cheese or cut hot dogs, they spark instantly - after 2 seconds. WHY??? It is not just my microwave - others too.

Answer 1

There is no reason the microwave should cause those foods to catch fire.  The only explanation is that there is metal in your cooking dishes that you are unaware of.

Answer 2

microwave radiations will make particles(objects size in the order of micro wave wave length) to vibrate...so that when we keep food ..it has water molecules ..thus when u pass MW through it ..it will only make water molecules to vibrate..so that vibration causes friction..and heat is produced.

if u keep anything that doesn't have water molecules will not get heated because there is no friction due to vibration....

thus heat is generated due to vibration of particles whose size is in order of MW wavelength (like water molecule)...it is this property we employ to cook food...

Answer 3

I'm not too sure, maybe there are iron particles in there that cause it? Microwaves work on the principle of generating Microwaves(which operate at 2.4GHz). The reason they use 2.4GHz is because that is an ideal frequency to heat up water molecules. So in a sense, your microwave oven does not heat the food itself, rather it heats the water molecules in your food. So there really is no explanation as to why the microwave causes those food items to spark, other than them having enough iron to cause a spark.

Answer 4

Whoa, it could be a chemical in it or something? It's not dangerous to your microwave though, when I microwave hot dogs they pop and stuff and that's just cause of air bubbles inside of the meat - I can't imagine broccoli or cheese etc to have air bubbles in it :s must be chemicals?xD