Suppose an iphone gave a little jolt when pressing the power button. Is that AC or DC current? The phone was connected to a laptop which was connected to a power outlet.


closed as off-topic by Nick Alexeev Apr 6 '18 at 20:46

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    \$\begingroup\$ Could it have been static electricity? If so, that consists of a short current spike. More information can be found in documents like this which describe the Human Body Model. \$\endgroup\$ – Daniel Apr 6 '18 at 20:31
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    \$\begingroup\$ @dandavis But it was connected to power outlet through the laptop, so won't that bring in AC current? \$\endgroup\$ – Henry Apr 6 '18 at 20:36
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    \$\begingroup\$ no, the connection to the laptop is DC, via the big warm block somewhere between the wall plug and barrel jack. \$\endgroup\$ – dandavis Apr 6 '18 at 20:39
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    \$\begingroup\$ If she was using a mystery charger in a place as effectively poorly regulated as China, she could've got hit with the full brunt of the mains. \$\endgroup\$ – schadjo Apr 6 '18 at 20:44
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    \$\begingroup\$ @Henry: no, that's a failed USB charger, not a laptop. a lot of chargers are shodily made and AC made it to the DC side, either from low clearance on the PCB or a poorly wound transformer. there's no way the laptop wouldn't get fried if the human got AC from it. so i guess that means it safer to charge from your laptop in china, as you'll have an indicator something bad is happening with the power... \$\endgroup\$ – dandavis Apr 6 '18 at 20:46

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