Metal in Microwaves: Glass or Metal?

[lisamay44]

A compact disc contains an extremely thin sheet of aluminum. If you put a larger block of metal in a microwave oven along with a CD and turn the oven on,

a) nothing significant happens
b) only the metal will spark and then melt
c) the metal will melt and the CD will spark
d) only the CD becomes hot enough to soften and sparks dance about its surface


I know that when you put a CD in a microwave D is what happens. I also know that if you put a large block of metal in the microwave nothing significant happens because thick metal conducts electricity well. But when you combine these two objects does anything different happen? My intuition is to go with D, since I don't think that the metal block would interfere with the microwaves that would cause the aluminum on the CD to spark, but I'm not entirely sure.


One more quick question...if metal bowls would help reflect microwaves through the food, why are most microwave safe bowls glass (i.e. Pyrex)? Is it better to cook foods in metal bowls or glass bowls?

 

[lzkelley]

I'm pretty sure the answer is D - like you said.
But the important thing to note is that even though nothing significant happens visually, in a short period of time with a large piece of metal --> important things are happening.
You should never use metal in the microwave. Small metal, as you know, will spark, burn melt, etc. large metal is bad because it reflects microwaves (again like you said), but that's bad - because it will damage the microwave, and increases the flux out of the microwave (although it still won't be very much). No shielding in a microwave oven is perfect; it works best when waves are being absorbed by something inside - like food. Thats why glass etc is good, because its transparent to microwave radiation - allowing it all to be absorbed in what you're heating.
(have you tried crumpled aluminum-foil?)

 

[Moetasim]

I would like to clarify that the use of metal in microwaves is not recommended due to the potential hazards it can pose. Metal can cause arcing, sparking, and damage to the microwave oven. Therefore, it is always advised to use microwave safe materials such as glass, ceramic, or plastic.

In the scenario described, it is likely that both the metal block and the CD will experience some heating and sparking, but the extent of these effects will depend on the composition and size of the metal block. The CD, being a thinner and smaller piece of metal, may experience more intense sparking and heating than the larger metal block.

Regarding the use of metal or glass bowls in microwaves, it is generally recommended to use microwave-safe glass or ceramic bowls. Metal bowls can cause arcing and damage to the microwave, and they also do not heat food evenly. Glass and ceramic materials are better at absorbing and distributing the microwaves, resulting in more even heating of the food. Therefore, it is generally safer and more effective to cook food in glass or ceramic bowls rather than metal ones.