What is the current in amperes if $1200 \textrm{ Na}^+$ flow across a cell membrane in $3.1 \; \mu \textrm{s}$? The charge on the sodium is the same as on an electron, but positive.

VIDEO TRANSCRIPT

This is Giancoli Answers with Mr. Dychko. We have to do some unit conversion here and also recognize that each sodium ion has a charge of one-plus. So each sodium ion is a charge of one electron. And so we multiply that by 1.6 times 10 to the minus 19 Coulombs per electron, and we're told there's 1200 sodium ions have passed in 3.1 microseconds. So we have 1200 times this conversion factor here. This is per 3.1 microseconds. And we have to always get our units into meters-kilograms-seconds, and so it's MKS units. So seconds here is what we need. So multiply it by 1 microsecond for every 10 to minus 6 seconds. The microseconds cancel. And we're left with 6.2 times 10 to the minus 11 amps is the current.