[6.1] Detecting gradient fields

...by looking for their 'swirliness' ("curl"). For each of the following sketches of a vector function of $(x,y)$, use the paddlewheel test to decide if the function could be the gradient of potential function, or not.

$\myv \grad\times\myv F = 0$, everywhere.

$\myv \grad\times\myv F$ is positive for $x\lt 0$ and negative for $x\gt 0$, and 0 along the $y$ axis.

$\myv \grad\times\myv F$ is positive (counter-clockwise circulation) everywhere.

Find one of your vector sketches from yesterday...
  • that has no swirliness.
  • that has curl.