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Microwaves are made from metal. When metal objects are cooked in it, it explodes.
Why does the microwave not react the same?

First of all, microwave ovens are specially designed to contain the waves of radiation inside themselves. The reason why metal objects inside an oven cause spraks and even explosions is that they act like antennas and absorb the microwaves, and the electric current generated in them produces an electric arc (connected discharge), which makes the sparks. However, the surrounding walls don’t act like an antenna because they don’t have the appropriate shape and they surround the microwaves without being immersed in them. Besides, whatever current it can cause is easily discharged by them into earth.

3 Responses

1. steveflatman Says:
   March 6th, 2010 at 5:25 am

   The internals of the microwave oven are exposed to microwaves but are earthed in such a way as to allow any current induced in them to be dissipated efficiently. Metallic objects within a microwave will act a antennas and when bombarded by microwave radiation, if insulated from a path whith which any induced current could be dissipated, these metallic objects become very effective heating elements. The heat generated in these elements when exposed to a flamable object is what is likely to cause a fire, or in dramatic cases an explosion.
   References :

2. Roundthread Says:
   March 6th, 2010 at 6:04 am

   And I thought it was to do with tuning. well there you go.
   References :

3. dnvr Says:
   March 6th, 2010 at 6:26 am

   First of all, microwave ovens are specially designed to contain the waves of radiation inside themselves. The reason why metal objects inside an oven cause spraks and even explosions is that they act like antennas and absorb the microwaves, and the electric current generated in them produces an electric arc (connected discharge), which makes the sparks. However, the surrounding walls don’t act like an antenna because they don’t have the appropriate shape and they surround the microwaves without being immersed in them. Besides, whatever current it can cause is easily discharged by them into earth.
   References :

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