Ghost Detectors: What Is 1 Milligauss?

[Razzor7]

"Ghost Detectors"

So I work at a popular tourist attraction that is well known for being "haunted." Needless to say, I get a lot of people asking about ghosts. I don't believe in ghosts. I need some kind of evidence to acknowledge stuff of the kind. Anyway, a week or two ago this couple showed up with a "ghost detector." I looked at it, and it was meter that measured milligauss. My physics class just blew over electromagnetism, so I only know what I've gathered from the internets. This is a measurement of the strength of an electromagnet field, yes? When I held it up to an exit sign, it went haywire. How significant is 1 milligauss? This thing went from like 1.5 to 6.0 milligauss.

Thanks.

 

[mgb_phys]

The Earth's field is about 400-600 milli Gauss depending on where you live.
Anything with AC wiring, a battery or an electric motor is going to give a significant field.

Or maybe your exit sign is haunted!

 

[Razzor7]

The Earth's field is about 400-600 milli Gauss depending on where you live.
Anything with AC wiring, a battery or an electric motor is going to give a significant field.

Or maybe your exit sign is haunted!

So is there some reason the "normal" reading was like 1.5 milli gauss and not 400-600? Or is it a matter of me remember the scale wrong/a faulty unit (I doubt that ghost detectors maintain a high quality standard).

Thanks for the info.

EDIT: typo

 

[mgb_phys]

The scale might be measuring extra field, although if it was really measuring 1mGa you would get that by just moving it a fraction.