Physics Works

While I generally trust that physicists do a good job in working out the details in their equations (at least the ones more than fifty years old) I am always impressed when I see them work.

At my job I was asked to produce a calculation of Induced Voltages on power lines. The problem was based around the idea that if a de-energized power line runs in parallel with an energized one than the magnetic fields from the in service line will induce a voltage in the other line. This is important because with large enough distances away from where a line is grounded, the voltage is high enough to electrocute a worker.

I set up a model entirely from Maxwell's equations and making some assumptions about power lines being straight lines. Then, since people's lives were on the line with the outcome of this calculation, we went out and measured actual induced voltages where several circuits were in parallel on the same poles for about a mile to compare with my calculations.

I just ran the calculations today in an excel program which includes the configuration of the conductors and the exact current on the parallel lines. Sure enough, Maxwell's Equations agree with experimental measurement to within about 5%. Remarkable. A few scribblings on paper and a few excel calculations actually do predict outcomes in the real world.