It's not DC actually, it's leaking AC. I think the shielding of the power adaptor picks up some induction (or capacitance?) and you can feel that when you brus

It's not DC actually, it's leaking AC. I think the shielding of the power adaptor picks up some induction (or capacitance?) and you can feel that when you brush over it with your hand. If you use a grounded lead (the 3-prong cable that comes with the adaptor instead of the 2-prong duckhead) it doesn't happen. Because the voltage that will flow to ground and won't build up. You can indeed feel it very clearly because it makes the surface feel rough and tickly. I'm also sensitive to it. A lot of computers do this, my PC-XT did this back in the 80s. But Apple is one of the few with an all metal case. A lot of other makes have metal but it's usually just a sheet and not connected to the actual ground. What I hate about Apple's current laptops is the sharp edges that cut into my wrists, and the keyboards that are too shallow to have real feedback. They seem made more to please the eyes, not the hands.