Can metal be placed in Microwave? Why or why not?

[seashell3130]

I'm doing a physics project on microwave ovens. I've been researching online and some sites say that you can place metal in microwave ovens because nothing will happen, and some say that you can't because metal reflects microwaves. I'm curious as to what the correct answer is and why. Thanks!

 

[fss]

If the microwave is large enough to accommodate the piece of metal; yes- the piece of metal can be placed in a microwave.

That was easy.

 

[seashell3130]

That was a very clever answer. However, I would still like to know more about this concept. I've always been told not to put metal into the microwave oven, but the more I read about it, the more it seems that there is no harm in doing so. I've also read about the concept that if the metal is placed in something that can absorb the microwaves (such as a spoon in water) than there is no harm. Why is this any different than if the metal is by itself?