posted on Nov, 26 2005 @ 12:48 PM
Microwave ovens produce an electric field inside. This electric field must be causing current to flow in the water, which then goes into the light
bulb and turns it on. The only way the bulb could be turning on is if electric current is flowing into it, so I suspect that this, or an explanation
much like it, is the correct answer.
If my explanation is correct, then if you put the light bulb in the microwave without any water or anything else, it shouldn't turn on. The electric
field is not strong enough in a microwave to overcome the dielectric breakdown of air. (if it was, your microwave would fill with sparks every time
you turned it on) The light bulb does not have any sharp points on it that would act like an antenna, so it should not cause dielectric breakdown
near the bulb.
I am curious, how bright does the bulb turn on? My guess is that it is rather dim, but visible. I would be extremely surprised if it glows very
bright at all.