Complete question:
Currents in dc transmission lines can be 100 A or higher. Some people are concerned that the electromagnetic fields from such lines near their homes could pose health dangers. For a line that has current 150 A and a height of 6.0 m above the ground, what magnetic field does the line produce at ground level?
Answer:
The magnetic field the line produces at ground level is 5 x 10⁻⁶ T.
Explanation:
Given;
current in the dc transmission line, I = 150 A
height above ground level, R = 6 m
The transmission line will be treated as current in a long straight wire.
Thus, the magnetic field produced at the ground level is given as magnetic field in a long straight conductor.
[tex]B = \frac{\mu_o I}{2\pi R}[/tex]
where;
μ₀ is permeability of free space = 4π x 10⁻⁷ T.m/A
[tex]B = \frac{4\pi*10^{-7} * 150}{2\pi * 6}\\\\B = 5*10^{-6} \ T[/tex]
Therefore, the magnetic field the line produces at ground level is 5 x 10⁻⁶ T.
