From: mbruins@trentu.ca (MICHAEL BRUINS)
Subject: Re: Street lights
News-Software: VAX/VMS VNEWS 1.41    
Organization: Trent University Computer Services Department
Date: Fri, 28 Aug 1992 15:21:00 GMT

In article <1992Aug24.210556.12275@newton.ccs.tuns.ca>, finneyrc@newton.ccs.tuns.ca (R Craig Finney) writes...dddd>This message is about street lamps going off as people walk under them.
>> 
>	When a person is electrocuted, his/her body becomes like
>	an electro-magnet, similar to making a magnet with an iron
>	nail and a battery.  The sensors in the street lamps
>	use a photo-sensitive cell with a relay.  The cell works
>	by the more light the less electricity that will travel 
>	through.  So the replay is needed.  This relay must be
>	very sensitive to work with small amounts of electricty.
>	So, I think that anyone that has been zapped will cause 
>	the magnet in the relay to shut the light off.
> 
>This is my theory.  I accept others.

Sorry Bubby but your theory has a few flaws.  First of all, when someone is 
electricuted he/she does not build any net charge.  Current merely passes 
through him/her and doesn't hang around.  (One can build up static charge 
if he/she is insolated but then gets zapped when he/she is grounded, ie 
from a carpet)  Magnets are made when the magnetic dipoles of a material 
are aligned (often due to electric current); however the human body is a 
non-magnetic material, and is not prone to having its dipoles so aligned.  
If you do not believe me let me ask you this.  Do you have forks and other 
utensils stick to you?  Does your watch continue to work after you put it 
on your arm?  Do you warp the picture on T.V. sets when you walk by?
I ask you these questions because in order for a magnetic field outside of 
the system to close the relay it must be very strong.  Even through the 
photodiode in the circuit does not send out much current, the relay is 
wound with many turns to insolate it from outside fields.  However you are 
correct in that a small current injected into the right part of the circuit 
could switch the relay.  If by some freak of nature someone was charged 
enough to "send" current 100 yards into such a circuit, he/she would be a 
walking lightning storm, discharging into every grounded object he/she came 
near.  It would take a potential difference of a few MegaVolts to discharge 
that type of distance.  This means the person would be dead (ie the 
electrons in his/her body would be striped away causing enough current to 
stop his/her heart and basically to rip him/her apart).  Also, that type of 
current would fry the diode and circuit probually causing it to blow (maybe 
even catch flame).

I must admit, I find this phenomenon very curious and even more so at how 
common it seems to be.  I haven't got a clue what's causing it except the 
flicker on and of every 5 mins theory.  (some other guy wrote that in)  
If anyone comes up with something concrete, please let me know!

-------------------------------------------------------------------------------
Your Phriendly Neighbourhood Physics Man
-------------------------------------------------------------------------------

Newsgroups: alt.folklore.ghost-stories