Re:“You don't have a voltmeter. Do you have a potato?”
by robocat on Thursday November 24, 2022 @11:45PM
(#33739278)
First example vid I found using those keywords: https://m.youtube.com/watch?v=kXaOP8O4HpI
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Re:“You don't have a voltmeter. Do you have a potato?”
by djmips on Friday November 25, 2022 @09:43AM
(#33742788)
Which seems to show that you use the pencil graphite as an electrode and spark it to ground. The 'fatness' of the spark determines the polarity.
Re:“You don't have a voltmeter. Do you have a potato?”
by userbinator on Friday November 25, 2022 @10:09AM
(#33743027)
Written description: https://navyaviation.tpub.com/14329/Figure-6-52-One-Method-O...
...although I haven't found any explanation online why it works. This method has probably been known for over a century, so I suspect it may be in some old physics books.