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phyzmatix
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Homework Statement
The picture shows (there's supposed to be a pic) a Helmholtz coil consisting of two circular coaxial coils, each of 200 turns and radius R = 25.0 cm, separated by a distance s = R. The two coils carry equal currents i = 12.2 mA in the same direction. Find the magnitude of the net magnetic field at point P, midway between the coils.
Homework Equations
[tex]B(z)= \frac{\mu_0}{2 \pi} \frac{\mu}{z^3}[/tex]
The Attempt at a Solution
I thought this was a pretty straightforward question and did the following:
[tex]\mu=NiA=(200)(12.2 \times 10^{-3} A)(\pi \times (0.25 m)^2) =4.79 \times 10^{-1} Am^2[/tex]
[tex]B(z)= (\frac{1.26 \times 10^{-6}H/m}{2 \pi})( \frac{4.79 \times 10^{-1}}{(0.125m)^3})[/tex]
[tex]=4.918 \times 10^{-5}T[/tex]
Now, the magnetic force from both coils are in the same direction, so I multiplied the above answer with two and got
[tex]\mbox{Force at P}=9.84 \times 10^{-5}[/tex]
However, this doesn't seem to be correct according to the answers I have...Could you tell me where I went wrong please? I'm clueless.
Thanks!
phyz