### Applet: A line integral gives z-component of curl

#### Applet loading

A line integral around a curve in a plane perpendicular to the $z$-axis gives circulation of the vector field corresponding to the $z$-component of the curl. Dividing this line integral the the area of the region inside the curve, and letting the curve shrink to zero gives circulation per unit area. This circulation per unit area is the $z$-component of the curl. You can drag the green point on the slider to shrink the curve to a point or drag the cyan point to change the location where the $z$-component of the curl is being calculated.

#### Applet links

This applet is found in the pages

#### General information about three.js applets

The applet was made using three.js and requires Javascript as well as a browser that supports WebGL. For most three.js applets, you can drag with the mouse to rotate the view, drag with the right button to pan, and zoom in/out with the mouse wheel. Many applets contain points that you can drag to change values of variables.