Answer:
0.107 m
Explanation:
The magnetic field at the center of a current-carrying loop is given by
[tex]B=\frac{\mu_0 I}{2r}[/tex]
where
[tex]\mu_0[/tex] is the vacuum permeability
I is the current
r is the radius of the loop
In this problem we have
I = 3.40 A is the current in the loop
[tex]B=20 \mu T=20\cdot 10^{-6}T[/tex] is the magnetic field at the centre of the loop
So, solving the formula for r we find
[tex]r=\frac{\mu_0 I}{2B}=\frac{(12.56\cdot 10^{-7} H/m)(3.40 A)}{2(20\cdot 10^{-6} T)}=0.107 m[/tex]
