A Quick and Intuitive Demonstration of (Magnetic) Resonance Using Just Three Magnets

• Yajun Wei ^[1]
  1. [1] Guangzhou University

     Guangzhou University

     China

     
• Localización: The Physics Teacher, ISSN 0031-921X, Vol. 62, Nº. 8, 2024, págs. 650-652
• Idioma: inglés
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• Resumen

  • Resonance is a topic covered in most introductory physics courses. Numerous demonstrations of mechanical resonance phenomena can be easily constructed using readily available items.1–5 Some educators have even proposed methods to observe resonance through the magnetic excitation of oscillation, leveraging the magnetic interaction between a current-carrying wire and a compass needle.6–8 These systems not only illustrate the concept of mechanical resonance, but also introduce students to magnetic resonance—a complex and vital technology in the modern world.

    Cookson et al. developed an inexpensive tabletop demonstration for magnetic resonance,8 which is very suitable for introductory physics courses. In their design, a compass is placed within the magnetic field of a permanent magnet. An alternating field, produced by a solenoid, then excites a resonant oscillation in the compass needle. Drawing inspiration from this innovative approach, we present a similar yet simpler and more intuitive demonstration in this paper.

    In our design, we use the rotation of a large compass instead of a solenoid to excite oscillation in a small compass needle. This simplification not only simplifies the setup by eliminating the need for a tone generator, solenoid, or computer, but also provides a tangible experience for students: they can directly observe the periodic shift of the magnetic field.