Quote (DanteX @ Sat, Apr 4 2009, 09:15pm)
The door of a microwave oven is carefully designed to reflect microwaves so that they can't escape from the oven. That mesh that you see in the door isn't plastic, it's metal. Metal surfaces reflect microwaves and, even though the mesh has holes in it to allow you to observe the food, it acts as a perfect mirror for the microwaves. Basically, the holes are so much smaller than the 12.2-cm wavelength of the 2.45-GHz microwave that the microwave cannot propagate through the holes. Electric currents flow through the metal mesh as the microwave hits it and those currents re-radiate the microwave in the reflected direction. Since the holes aren't big enough to disrupt that current flow, the mesh reflects the microwaves as effectively as a solid metal surface would.
ive never understood how you can make a hole small enough for light to pass but not microwaves (smaller wavelength than visible light). edit: holy crap i are wrong. always thought xray/gamma had longer wavelengths and micro had shorter wavelengths.
This post was edited by juliusjuice on Apr 5 2009 01:52pm