A High Power Line Carries a Current Of $1.0 \mathrm { kA }$

Multiple Choice

A high power line carries a current of $1.0 \mathrm { kA }$ . What is the strength of the magnetic field this line produces at the ground, $10 \mathrm {~m}$ away? $\left( \mu _ { 0 } = 4 \pi \times 10 ^ { - 7 } \mathrm {~T} \cdot \mathrm { m } / \mathrm { A } \right.$ )

A) $6.4 \mu \mathrm { T }$
B) $20 \mu \mathrm { T }$
C) $4.7 \mu \mathrm { T }$
D) $56 \mu \mathrm { T }$