Magnectic Field Magnetic Field and High-Voltage Power Lines                 Date : July 2016 Author : Alexandre April, Olivier Tardif-Paradis and Mathieu Riopel. College : Cégep Garneau Length : 1 to 2 hours Related concept(s) : Magnetic field generated by a straight wire with a current running through it, superimposition of magnetic fields, three-phase current.     In this activity, the students have to calculate the magnetic field produced by a set of three straight, parallel wires, using the principle of superposition. The introduction also explains the basics concerning three-phase current, which is used to transmit electricity in high-voltage lines.