Assertion: detector's contact | /r/CreatedBy | a piece of mineral
Facets:
Source sentences:
text: Graphing the current as a function of voltage across a contact made by a piece of mineral touched by a wire cat whisker, he found the result was a line that was flat for current in one direction but curved upward for current in the other direction, instead of a straight line, showing that these substances did not obey Ohm's law.