I've often wondered why I can tell by touch whether a device is charging or not from the slight "vibration" sensation I get when gently touching the case.
It's often noticeable if you have a point contact of metal against your skin; sharp edge / screw / speaker grill, etc. Once you have decent coupling between your body and the laptop, you won't feel the tingle / zap.
They're called Y-caps if you want to delve deeper into them and their use in power supplies.
I've often wondered why I can tell by touch whether a device is charging or not from the slight "vibration" sensation I get when gently touching the case.