Magnetic field of a linear octupole

TL;DR

This study measures the magnetic field of a linear octupole using a smartphone sensor to verify the theoretical quintic decay of the x-component with distance.

Contribution

It demonstrates a practical method to measure complex magnetic fields using accessible smartphone technology and compares experimental results with theoretical predictions.

Findings

Magnetic field measurements align with the quintic decay prediction.

Smartphone sensors can effectively measure complex magnetic fields.

Experimental data supports theoretical models of octupole magnetic fields.

Abstract

We measure the magnetic field produced by a linear octupole formed by four magnets placed in such a way that both their magnetic moments and their quadrupole moments cancel each other. The magnetic field is measured with the magnetic sensor of a smartphone together with a suitable app, using the Android operating system. The main objective is to determine the dependence of the x-component of the magnetic field with distance and compare with the theoretical result that tells us that this dependence is a quintic decrease.