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What is the current when a typical static charge of $0.250 \mu\textrm{C}$ moves from your finger to a metal doorknob in $1.00 \mu\textrm{s}$?
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Final Answer

$0.250 \textrm{A}$

Solution Video

OpenStax College Physics Solution, Chapter 20, Problem 3 (Problems & Exercises) (0:44)

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Video Transcript

This is College Physics Answers with Shaun Dychko. So when this spark from your finger to the doorknob, 0.25 micro-coulombs of charge have moved and that is 0.25 times ten to the minus six coulombs because the prefix micro means multiply by ten to the minus six. It happens in a time of 1 micro-second which is one times ten to the minus six seconds. So the current is that charge divided by the time. So that's 0.25 times ten to the minus six coulombs divided by one times ten to the minus six seconds, change that to seconds there, and well, these ten to the minus sixes cancel. Then 0.25 divided by one, we don't even need a calculator for that, we can just say 0.25. Coulombs per second is abbreviated with the unit amps.