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## Homework Statement

Find B at the center of the 3.2-cm-radius semicircle in the figure(Figure 1) . The straight wires extend a great distance outward to the left and carry a current I=6.4A.

## Homework Equations

(Magnetic field for a current carrying loop)

[itex]\overrightarrow{B}=\frac{\mu_0I}{2R}[/itex]

## The Attempt at a Solution

- Assuming that the two straight segments create magnetic fields that just cancel each other out, since their currents run opposite of each other.
- Assuming the unshown segment somewhere far off to the left has insignificant influence (I think that's what "extend a great distance outward to the left" implies)

So I'm left with a semi-circle of radius .032 m and I need to find the magnetic field at the center.

Logically the field will just be half of that of a full circle, so:

[itex]\overrightarrow{B_\frac{1}{2}}=\frac{1}{2}\frac{\mu_0I}{2R}=\frac{\mu_0I}{4R}=\frac{8.8542\cdot 10^{-12}\cdot 6.4}{4\cdot 0.032}=4.4271\cdot 10^{-10}[/itex]

Rounds to 4.4E-10 (Mastering Physics asks for two significant figures)

Program marks it as incorrect. I'm not sure where to go from here. I considered magnetic moment, but aside from halving the magnetic moment, I'm not sure what I could do.

Thanks in advance!