A long, straight wire lies on a horizontal table and carries a current of 1.45 µA. In a vacuum, a proton moves parallel to the wire (opposite the current) with a constant speed of 3.00 104 m/s at a distance d above the wire. Determine the value of d. Ignore the magnetic field due to the Earth.

Question

A long, straight wire lies on a horizontal table and carries a current of 1.45 µA. In a vacuum, a proton moves parallel to the wire (opposite the current) with a constant speed of 3.00  104  m/s at a distance d above the wire. Determine the value of d. Ignore the magnetic field due to the Earth.

I got d=0.8939 but that was incorrect
   B = mg /qv  used this to find B 
 B = μo*I / 2πd  used this to find d

drwls · Answer

What are the units of d? Meters? 2 π d * (B/μo) = I by Amperes Law. I agree with your approach and equations.