What is the magnetic top?
O topmagnetic, which bears the trade name of Levitron, is a toy that uses the principles of magnetic force and of the rotational inertia to make a top levitate before our eyes.
The working principle is simple: a base that contains a magnet ceramic and with a very intense magnetic field is used to repel a magnet (also produced in ceramic material) in the form of a ring installed in the top. The magnetic fields generated by the two components of the toy are aligned with poles equal, so that the repulsive magnetic force is favored.
Levitron's balance is delicate and its levitation occurs at a height of approximately 4 cm from the base. The toy's revolution frequency can reach about 20 revolutions per second, however, if the top is not horizontally aligned with its base or its rotation frequency varies greatly, he loses O balance, just like a conventional top.
The material used to make the magnets is ceramic to prevent the induction in chainselectric in its magnetic parts, thus decreasing the dissipation of its kinetic energy.
How does the magnetic top work?
The conventional top is supported by a vertical force, which is the reaction to the compression from the metallic tip to the surface. This vertical force is the Normal, formed in the same direction as the weight, with the opposite direction and the same module.
Similarly, for levitation to occur, the magnetic force on the top is formed in the same direction as the force. weight that acts on it, however, with the opposite sense, and must necessarily have a module equal to or very close to it; otherwise, the toy loses its balance and falls.
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The top's high rotation speed gives it a property of objects that are in rotational movement: o time of inertia. It is the amount of movement related to rotations and works as follows: the higher the rotation speed of the mobile, the more stable its balance will be, similarly to the behavior of the wheels of bicycles and motorcycles in movement.
As the magnetic top is not supported on the ground, the duration of its rotational movement is prolonged, but not lasts forever: even though it's small, the air resistance ends up dissipating part of the device's energy through the friction.
Another limiting factor to the toy is the temperature operating time: after a certain temperature value, the magnets lose their magnetization and no longer have magnetic properties. This temperature is called Curie temperature.
The phenomenon of magnetic levitation, responsible for making Levitron so interesting, is a principle used by several technologies, such as trains which float on their tracks because of the repulsion or attraction between magnetic poles. Thus, magnetic tops are an invitation to view this physical phenomenon of great scientific and technological interest.
*Image credits:Magitek
By Rafael Hellerbrock
Graduated in Physics
Would you like to reference this text in a school or academic work? Look:
HELERBROCK, Rafael. "Magnetic Top (Levitron)"; Brazil School. Available in: https://brasilescola.uol.com.br/fisica/piao-magnetico-levitron.htm. Accessed on June 27, 2021.
