A long, straight wire lies on a horizontal table and carries a current of 1.20 A. In

Question:

A long, straight wire lies on a horizontal table and carries a current of 1.20 µA. In a vacuum, a proton moves parallel to the wire (opposite the direction of the current) with a constant velocity of 2.30 x 104 m/s at a constant distance d above the wire. Determine the value of d. (You may ignore the magnetic field due to Earth.)