Answer :
Answer:
[tex]6.66\cdot 10^{-12}T[/tex]
Explanation:
The magnetic field produced by a current-carrying wire is given by
[tex]B=\frac{\mu_0 I}{2\pi r}[/tex]
where
[tex]\mu_0[/tex] is the vacuum permeability
I is the current
r is the distance from the wire
In this problem we have
[tex]I=0.040 \mu A=4\cdot 10^{-8}A[/tex]
r = 1.2 mm = 0.0012 m
So the magnetic field strength is
[tex]B=\frac{(4\pi \cdot 10^{-7} H/m)(4\cdot 10^{-8}A)}{2\pi (0.0012 m)}=6.66\cdot 10^{-12}T[/tex]