Answer:
The magnetic field 50m below the transmission line is 4 micro Tesla.
Explanation:
The magnetic field [tex]B[/tex] due to a current carrying wire at a distance [tex]R[/tex] is
[tex]B = \dfrac{\mu_o I }{2\pi R }[/tex]
where [tex]\mu_o = 4\pi*10^{-7}H/m[/tex] is the magnetic constant.
For the case of the power line we put in [tex]I = 1000A[/tex] and [tex]R = 50m[/tex] to get:
[tex]B = \dfrac{(4\pi*10^{-7}) (1000A) }{2\pi (50m) }[/tex]
[tex]B = 4\mu T[/tex].
Thus, the magnetic field 50m below the transmission line is 4 micro Tesla.
