In the US the mains power runs at 115V, 60 Hz. With an oscilloscope, I can see this mains hum everywhere. It radiates from the AC power lines throughout the lab and the whole city. Appearently our bodies make great antaneas for 60 hz: touching the oscilloscope probe shows a 9V RMS @ 60 Hz. Like a nine volt battery! From my body!
I also noticed that the using the probe clip picks up more mains hum than just the probe tip.
I’m learning how to use the scope. I suspect it will become my main measurement tool.
Today I received a Tektronix p6109 general purpose probe compatible with my scope: