Oscilloscope question

[LuisLDias]

Today I was working on my new project, when a turn my oscilloscope a say some strange wave forms on it. The leads were plugged  but not connected to anything.
I recently change to a new home and it the first time I saw this. The freq is about 50Hz. It's some kind of main's interference?

[Keysight DanielBogdanoff]

The probes are basically an antenna, so there's generally going to be something picked up from your environment.  You can try moving around the probe cables, coiling them, etc. and minimize it.

Generally, though, it won't have much (or any) impact on your measurements.

[danadak]

Its 20 mS period, 50 Hz, AC line pickup, very common problem as buildings
are full of power wiring radiating magnetic and E fields.

The fact the waveforms not pure sinusoid has to do with AC line loads, motors,
microwaves power transformers, LapTop bricks, small appliances....
all generating crud.

Regards, Dana.

[Paul Price]

You might be using a desk lamp on or above your workbench that has a fluorescent tube or VFL lamp with a ballast.
The sharp spike in the observed waveform is the flash-over of the gas in the tube as the voltage rises high enough to cause an avalanche of current flow, the  short ramp up next is due to the lamp's gas drawing increasing current thorugh the ballast,  and the sharp drop back down to 0-V is the lamp voltage falling below the ignition point and current stops flowing..the same waveform repeats on the negative side of the cycle.