Two long straight current-carrying wires run parallel to each other. The current in one of the wires is 4.1 A, their separation is 3.3 cm and they repel each other with a force per unit length of 2.9  10-4 N/m. (a) Determine the current in the other wire.   b) Determine what will happen if the direction of one current is reversed and tripled. (Select all that apply.) 1) The wires are attracted to each other. 2) The wires are repelled by each other.

A 5.0-m section of a long, straight wire carries a current of 10 A while in a uniform magnetic field of magnitude 8.0103T . Calculate the magnitude of the force on the section if the angle between the field and the direction of the current is (a) 45°; (b) 90°; (C) 0°; or (d) 180°.

Does increasing the magnitude of a uniform magnetic field through which a charge is traveling necessarily mean increasing the magnetic force on the charge? Does changing the direction of the field necessarily mean a change in the force on the charge?

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 current) with a constant speed of 2.30 × 104 m/s at a distance d above the wire. Ignoring the magnetic field due to the Earth, determine the value of d.