That's okey dude, you still get more marks in MC than me
Also, yes you are right that devices are not meant to use the same frequency, however this is actually part of the problem, with all devices generally limited to a certain range, which gets overcrowded.
Or that's the way I think of it anyway =/
Probably a good thing I dropped physics.
Also, I just re-read the question, notice it says "Elecromagnetic Radiation". It doesn't say anything about other devices even interfering with it. When elecromagnetic radiation is mentioned what do you think of? It should be something big, like a very big solar flare from the sun, sending excessive radiation to Earth, and you always hear on the news when this happens that wireless networks across the planet are experiencing problems, etc.