# Homework Help: Magnetic Field at the center of a square loop

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1. Mar 20, 2016

### Elvis 123456789

1. The problem statement, all variables and given/known data
A square wire loop 12.0 cm on each side carries a clockwise current of 15.0 A

Find the magnitude of the magnetic field at its center due to the four 1.30 −mm wire segments at the midpoint of each side.

2. Relevant equations
B = (μ0*I)/(4π)*(2a)/(x√(x^2+a^2))

3. The attempt at a solution
I used the above equation for magnetic field at the center of the square loop due to one wire and then multiplied it by 4 since the contribution due to each wire segment is the same by symmetry.

B = 4*(4π*10^-7*15)/(4π)*(2*0.06)/(0.06*√(0.06^2+0.06^2))

B = 1.41*10^-4 T

This answer is wrong and I don't know why

2. Mar 20, 2016

### BvU

It looks to me you found the magnetic field at its center due to the four whole 12 cm wire sides. What about these strange 1.3 mm segments ?

3. Mar 20, 2016

### Elvis 123456789

I am actually not even certain what is meant by that part, I kinda just dismissed it as unnecessary information.

4. Mar 20, 2016

### BvU

What if it is serious information ? You'd get almost a factor 100 less !
But I grant you that I too find it a weird way to formulate an exercise.

5. Mar 20, 2016

### Elvis 123456789

So instead of considering the contribution to the magnetic field due to each entire wire segment, am I only supposed to consider the contribution due to the middle 1.3mm piece of each segment? The question seems much more ambiguous to me now that you brought that to my attention.

6. Mar 20, 2016

### BvU

That's what it says to me.

7. Mar 20, 2016

### Elvis 123456789

Yes this was the case indeed, thanks for your help sir.

8. Mar 20, 2016

### BvU

You're welcome