Mobius wrote:The human body operates at 50Hz - which is exactly the reason that New Zealand power (240V AC ~50Hz) is so dangerous: it causes muscles to contract and because of the frequency, if your hands are grabbing a live wire, it is impossible to let it go. At 110V AC ~60Hz (Like you guys sensibly have!) then you could let go of the live wires.
Wow. That much inaccuracy from Mobi
ELECTRICITY-PHYSIOLOGICAL EFFECTS wrote:Relatively low currents can cause muscular contractions that may prevent a victim from letting go of an energized object. The threshold of this current is a function of condensity, contact area, contact pressure and individual variations. Virtually all men and almost all women and children can let go at currents up to 6 mA. At 10 mA it has been observed that 98.5% of men and 60% of women and 7.5% of children can let go. Only 7.5% of men and no women or children can let go at 20mA. No one can let go at 30mA and greater.
[..]
The frequency of the electrical signal responsible for electrical accidents is generally known. In Europe, it is almost always 50 Hz and in the Americas, it is generally 60 Hz. In rare cases involving railways in countries such as Germany, Austria and Switzerland, it may be 16^(2/3) Hz, a frequency which theoretically represents a greater risk of tetanization and of ventricular fibrillation. It should be recalled that fibrillation is not a muscle reaction but is caused by repetitive stimulation, with a maximum sensitivity at approximately 10 Hz. This explains why, for a given voltage, extremely low-frequency alternating current is considered to be three to five times more dangerous than direct current with regard to effects other than burns.
See
http://www.ilo.org/encyclopedia/?doc&nd=857100207&nh=0
Besides that, your eyes operate analog. So does an LCD BTW -- the background light is steady, so is the picture when there are no changes. There are no interferences w/ fluorescent light unless the picture changes constantly at 60Hz. If he sees stuff w/ a steady LCD picture I would indeed recommend a visit to the doctor. Ghosting happens when there's a change in the picture and is caused by the time the crystals need to realign themself to the new condition.
Edit: I hate fluorescent light as well, makes me edgy. Possible explainations:
Fluorescent lamp wrote:Many people find the color spectrum produced by some fluorescent lighting to be harsh and displeasing. It is common for a healthy person to appear with a sickly bluish skin tone under fluorescent lighting. This is due in part to the presence of prominent blue and green lines emitted directly by the mercury arc and in part to the type of phosphor used. Many pigments appear a slightly different color when viewed under fluorescent light versus incandescent. This is mainly the case with fluorescent lamps containing the older halophosphate type phosphors (chemical formula Ca5(PO4)3(F,Cl):Sb3+,Mn2+), usually labeled as "cool white". The bad color reproduction is due to the fact that this phosphor mainly emits yellow and blue light, and relatively little green and red. To the eye, this mixture looks white, but light reflected from surfaces has an incomplete spectrum.
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Fluorescent lamps do not give out a steady light, instead they flicker (fluctuate in intensity) at a rate that depends on the frequency of the driving voltage. While this is not easily discernable by the human eye, it can cause a strobe effect posing a safety hazard in a workshop for example, where something spinning at just the right speed may appear stationary if illuminated solely by a fluorescent lamp.
And of course the interference w/ CRTs.
See
http://en.wikipedia.org/wiki/Fluorescent_lamp
Edit2: maybe the reason for the strain is a broken backlight -- if you "drag" your eyes quickly accross the picture, do you see a stroboscope effect ? If so, return the monitor and get a replacement.
My crt i was running at 80hz
