Science Forums 2

[sanctus]

Or more intuitively curl is how a vector field turns :-). Imagine you are at a point A in a given vector field (= a "map" where ate every point you associate a vector, in 2D you can imagine the cartesian plane with arrows at every point). Examples of a vector field with no curl are a map where all the arrows point in the same direction or one where all the arrows point to the center. An example of a vector field with curl would be a map where all the arrows are tangent to circles around the center.

Physically, the first example could show the electrical field between a negatively and positively charged (infinite) "planes" (i.e imagine a vertical line at x=-1 charged positively and one at x=1 charged positively then the field would be horizontal arrows, they have to be of inifinite length otherwise curly stuff happens at the borders);
the second example could be the electrical field of a charge situated at the center;
the third example, could be the velocity vector field of particles of water going down a sink