This field has curl, with the direction of the curl pointing out of the page (make sure you can use your right hand to get this result). Notice that the piece of red confetti in the flow also rotates in the proper sense for the curl to point out of the page. This vector field is given by Aphi = kr, in cylindrical coordinates, where Aphi is the phi component of the vector field. Look up the formula for the curl in cylindrical coordinates and convince yourself that it does point out of the screen.

---

 

---

 
Now, to go to another page with curl, click here.