Microwave oven generate around 1 KW of power. If this energy is dumped on a electronic device, say wifi router, gsm phone or fm receiver etc, what will happen? Will the devices be damaged? By dumping I mean the magnetron at a distance of 1m or less from the electronic device and assume body cage absent.
Yes, the device will be damaged. See https://www.youtube.com/watch?v=vI8JTUql3bQ for reference... Sure, inside the body cage, the microwaves are bouncing around and may be more concentrated, but even with no cage, the effect is the same - microwaves hitting thin metal (as on a PCB) causes arcing, and consequently damage. You may not get an explosion, but you definitely won't get working devices.