Demonstrations of magnetic phenomena: Measuring the air permeablity using tablets

TL;DR

This paper demonstrates an experimental method using tablets to measure magnetic field dependencies and accurately determine air permeability, confirming theoretical models with simple data fits and error analysis.

Contribution

It introduces a novel, accessible approach for measuring magnetic phenomena and air permeability using common tablets and straightforward data analysis.

Findings

Magnetic field B varies as z^{-3} with axial distance.

Air permeability μ_air is measured with good accuracy.

The method confirms theoretical magnetic field dependence and permeability values.

Abstract

We use a tablet to determine experimentally the dependencies of the magnetic field (B) on the electrical current and on the axial distance from a coil (z). Our data shows a good precision on the inverse cubic dependence of the magnetic field on the axial distance, $B \propto z^{-3}$. We obtain with good accuracy the value of air permeability $\mu_{air}$. We also observe the same dependence of $B$ on $z$ when considering a magnet instead of a coil. Although our estimates are obtained through simple data fits, we also perform a more sophisticated error analysis, confirming the result for $\mu_{air}$.