314. How do metal rods short out the microwaves?
If you arrange a metal rod so that it's parallel to a microwave's electric field, the microwave will push electric charges up and down that rod. This moving charge will waste some of the microwave's energy by creating heat in the rod. But the main effect will be that the rod will reflect or scatter the microwave. The moving charge will emit its own microwave and this new microwave will interfere with the original one.