Many readers will have seen this image or something similar. Fluorescent tubes are connected to earth near a high-voltage electricity cable and the tubes glow “magically” without any obvious electrical connection.
Quiz question: is the energy transferred to the fluorescent tube from the electricity cable by
a) electrical current flowing from the cable to the ground via the air and tube due to the high voltage
b) electro-magnetic induction of a voltage at the top end of the fluorescent tube by an electro-magnetic field generated by the alternating current in the cable
or c) something else (suggest what else it might be with your answer)
Bonus question: If the same cable was placed underground at the same distance below ground from the top of the fluorescent tube as it was above it to start with, with the same voltage and current passing through it, would the fluorescent tubes still glow? (Assume that the cable is electrically insulated and that the ground is not made of anything too surprising.)
The floor is yours.
If all in the world were blind would there be light to see it ?
Yes but I’d like to know why a blind society would develop fluorescent (or any other type) lighting!
Significant electromagnetic fields can be measured beneath power lines so banks of fluorescent tubes placed under them can be seen to glow as a result of the induction effect. Spending much time in close proximity to pylons is a bad idea, BE.
c) They’re not ordinary flourescent tubes, they are the new iLight range from Apple. Each has its own Apple id and is logging in to the Apple store via a wireless data link to the iPower lines above them. They are shining with a white light as that is the colour of the video they are downloading from the Apple Store, designed to provide uniform lighting to your iHome (this would normally be around the iLights but the subscriber can’t afford it yet, and is also waiting for the less buggy iHome 7.1 before he downloads it). Other downloadable lighting videos include softer mood lighting and disco lights. Sorry, iMood lighting and iDisco lights.
Either that, or MTG is right.
A buried cable wouldn’t show this as the earth would be too strong a dielectric, so the range of the fields would be much shorter than in air.