일반물리학 2 — Magnetic Fields: Problem 33

33 A horizontal power line carries a current of 7000 A from south to north. Earth’s magnetic field ($60.0 \mu\text{T}$) is directed toward the north and inclined downward at $70.0^\circ$ to the horizontal. Find the (a) magnitude and (b) direction of the magnetic force on 100 m of the line due to Earth’s field.