Did you learn this one weird trick from a mother just like you or I?
I think his point was simply that the Earth itself has a magnetic field. I had to look up its strength:
http://en.wikipedia.org/wiki/Gauss_(unit)#Typical_valuesConverting to milligaus, that's 310-580 milligaus at the Earth's surface. If I understand your statement correctly, that's 3 to 5 times the 100 milligaus near a power supply.
0.31–0.58 gauss – the Earth's magnetic field at its surface
One presumes your detector has been calibrated so the Earth's field is not being measured. This doesn't make the field disappear, it simply removes it from the instrument's reading.
How is the device able to differentiate between the Earth's field and fields generated by electrical devices?
Find a power supply that gives off a greater-than-100 milligaus reading, and sleep with it next to your head for a week. See what happens.
How is the device able to differentiate between the Earth's field and fields generated by electrical devices?
Find a power supply that gives off a greater-than-100 milligaus reading, and sleep with it next to your head for a week. See what happens.
Precious bodily fluids... almost gone...
Save yourselves!
Both telling people they are in danger and laughing at people for thinking EMF's do harm are both polaric and untruthful. It's an opportunity to protect yourself if you feel you need it.