Magnetic fields produced by electric railways

TL;DR

This paper presents a simple, educational experiment using smartphone magnetometers to measure magnetic fields from electric railways, comparing results with models and Earth's magnetic field for educational purposes.

Contribution

It introduces an accessible method for students to explore magnetic fields of power lines through a practical experiment using common devices.

Findings

Experimental magnetic field measurements match model predictions

The method is suitable for educational field trips

Students learn modeling and estimation of magnetic fields

Abstract

We propose a simple experiment to explore magnetic fields created by electric railways and compare them with a simple model and parameters estimated using easily available information. A pedestrian walking on an overpass above train tracks registers the components of the magnetic field with the built-in magnetometer of a smartphone. The experimental results are successfully compared with a model of the magnetic field of the transmission lines and the local Earth's magnetic field. This experiment, suitable for a field trip, involves several abilities, such as modeling the magnetic field of power lines, looking up reliable information and estimating non-easily accessible quantities.