A cross section of a circular wire loop carrying an
unknown current is shown. The arrows represent the direction
of the magnetic field. The color of the arrows represents the magnitude of
the field with magnitude increasing as the color changes from blue to green to
red to black. You can double-click in the animation to add magnetic field
lines, click-drag the center of the loop to reposition it, and click-drag the
top or bottom of the loop to change its size.
You may also add a compass by clicking the “Add Compass” link.
Does current flow out of the red (top) end or the blue (bottom) end?