As
you notice in the illustration at right (click on the illustration for a
VRML model of the circular loop), the coil is supplied current I
through two straight sections. You might wonder if perhaps that will
affect the magnetic field in any way. It turns out that it will not
because the fields created will nullify one another.Let's do another derivation to illustrate this. Again, we will find the magnetic field and break it into components at point P shown in the illustration:
(Equation 6-67)
But because of symmetry, you can tell that the y-component is cancelled out by the opposite sides of the ring. So only the x-component is matters, so we integrate it and get:
(Equation 6-68)
And look what familiar equation you get when point P is at the center of the loop (x = 0):
![B[x] = (mu 0)I/2a](6-69.gif){kind=small}
(Equation 6-69)
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