Thus,
 
(
)
π
0
2
2
d
d
4
I l
B
x
R
=µ
+
(4 13)
FIGURE 4 9 Magnetic field on the
axis of a current carrying circular
loop of radius R Shown are the
magnetic field dB (due to a line
element dl ) and its
components along and
perpendicular to the axis