Abstract:

This work presents an innovative laboratory proposal for introductory physics courses based on the experimental study of the magnetic field generated by a linear octupole using a smartphone. The activity is designed within a competence-based learning framework, promoting active student engagement through inquiry, data analysis, and model validation.

The experimental setup consists of four identical ferrite magnets arranged to cancel both dipole and quadrupole contributions, isolating the octupole behaviour. The magnetic field is measured using the built-in magnetometer of a smartphone and a dedicated application, allowing students to work with accessible and familiar technology. This approach reduces experimental complexity while maintaining scientific rigor.

From a pedagogical perspective, the core objective is not only to measure the magnetic field but to guide students toward discovering the underlying physical law. By recording the magnetic field as a function of distance and applying logarithmic transformations, students perform a linear regression that reveals the expected power-law dependence. The experimental exponent obtained (n ≈ 5.01 ± 0.08) closely matches the theoretical prediction for an octupole (n = 5), with a relative deviation of only 1.6 %. This agreement reinforces the connection between theory and experiment.

The activity is structured to foster key competencies: experimental design, critical data interpretation, uncertainty awareness, and the use of digital tools for scientific analysis. In addition, it encourages students to reflect on scaling laws in physics, comparing monopole, dipole, quadrupole, and octupole behaviours, thereby deepening conceptual understanding.

This proposal aligns with modern trends in physics education that emphasize low-cost, technology-enhanced, and student-cantered learning environments. The use of smartphones—devices already integrated into students’ daily lives—facilitates accessibility and increases motivation, transforming them into powerful scientific instruments.

The results suggest that meaningful learning can be achieved through carefully designed experiments that prioritize conceptual discovery over technical sophistication. This laboratory experience provides a scalable and adaptable model for teaching advanced physical concepts in an intuitive and engaging way, making it particularly suitable for first-year STEM courses.

Keywords:

Learning physics, octupole, smartphone, digital tools, STEM courses.