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**1. Homework Statement**

https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-prn1/553004_1959186995753_1725123128_934768_456680196_n.jpg [Broken]

In case the words are too small:

I

_{2}= 6.61I

_{1}

The net magnetic field at center of loop is 0.

I'm looking for the radius of the loop

**2. Homework Equations**

for straight wire: B=(u

_{0}*I)/(2[itex]\pi[/itex]*r)

for loop: B= (u

_{0}*I)/(2*r)

**3. The Attempt at a Solution**

So, since the two magnetic fields are perpendicular to each other: √(B

_{1}

^{2}+B

_{2}

^{2})=0

I tried to find H in terms of R by using the right hand rule. I2/I1=(B2*H*[itex]\pi[/itex])/(B1*R) so H= -(6.61R/[itex]\pi[/itex])

But now I'm stuck, and I don't know if my work so far is even right.

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