4. Two very long straight wires carrying current I as seen in the figure below, are separated by a distance a. In between the two wires, there is a circular conductor of radius R = " 2 The current flowing through this circular conductor is I, = -. The currents are insulated from each other. Mark the directions of the magnetic fields generated by each of these three conductors at the center of the circular loop and work out an expression for the net magnetic field vector at this point, in unit vector notation.