A simple example of the Biot-Savart law is given with a current carrying loop for a quater of a circle as shown in Figure 1.
The differential line element dl is perpendicular to
, so the Biot-Savart law simplifies from the definition of the cross product
Note that the direction is into the web browser, so we have a
. For the differential dl of a circular arc
plugging this in and setting up the integral gives
which simply yields
As of this snapshot date, this entry was owned by bloftin.