Field of a Long Wire: Two Long Parallel Wires Carry

Multiple Choice

Field of a long wire: Two long parallel wires carry currents of 10 A in opposite directions. They are separated by 40 cm. What is the magnitude of the magnetic field in the plane of the wires at a point that is 20 cm from one wire and 60 cm from the other? (μ₀ = 4π × 10^-7 T ∙ m/A)

A) 1.5 µT
B) 3.3 µT
C) 6.7 µT
D) 33 µT
E) 67 µT