Magnetic flux due to current in two vertical parallel wires
If two parallel wires are arranged side by side vertically and carry currents in the same direction the magnetic flux in a horizontal plane close to the wires is as shown in Fig. 36.16. A neutral point is formed between the wires, its exact position depending on the relative strengths of the currents. Note that some of the’ magnetic flux surrounds both wires.
Fig. 36.17. Magnetic flux pattern in plane at right angles to two parallel currents in opposite directions (lateral repulsion between magnetic field lines results in repulsion between wires carrying the currents) Michael Faraday visualized a magnetic field as containing magnetic field lines which possessed longitudinal tension and lateral (= sideways) repulsion. In this sense they may be compared with the electric field lines described on page 380. The tension in the lines sets up a force which pulls the two wires inwards. On the other hand, two parallel wires carrying currents in opposite directions repel one another since the magnetic field lines between them are in the same direction and hence show lateral repulsion (Fig. 36.17).