What is the magnetic field strength, in units of microTesla (T), at a distance of 6.3 cm from a long straight wire carrying a current of 6.5 A?

Answer:
[tex]2.1 \mu T[/tex]
Explanation:
The magnetic field strength 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,
I = 6.5 A
r = 6.3 cm = 0.063 m
So, the magnetic field strength is
[tex]B=\frac{(1.256\cdot 10^{-7} H/m)(6.5 A)}{2 \pi (0.063 m)}=2.1\cdot 10^{-6} T=2.1 \mu T[/tex]