Understanding Solenoids: A Comprehensive Guide to Magnetic Fields and Applications

Industrial applications of solenoids and coils include valves and electric motors due to the magnetic field they generate. The video discusses how to calculate this magnetic field and explores various curiosities.

A solenoid is a coil of wire with a high density of turns that can produce a strong magnetic field when a current passes through it. The direction of the magnetic field is determined by the right-hand rule.

When a current flows through a coil, it generates a strong and uniform magnetic field inside. The magnetic field lines resemble those of a straight magnet, but the coil's field disappears when the current stops.

Electromagnetic valves are constructed using the magnetic field generated by coils. These valves can open or close based on the presence of a magnetic field, influencing the flow of substances.

The video explains how to calculate the magnetic field inside a solenoid using Ampere's law. The circulation of the magnetic field along a closed path is related to the current enclosed by that path.

By studying a solenoid cut in half, the direction of current flow is observed. Applying Ampere's law involves forming a closed path with four straight segments to calculate the magnetic field.

The magnetic field outside the solenoid is dispersed and far from its possibilities, resulting in a nearly zero field. This means that certain segments, such as tramo 2, contribute nothing to the integral.

Inside the solenoid, the magnetic field vectors and differential length are parallel, making the cross product zero. The magnetic field is uniform, simplifying the integral to the product of the field's magnitude and the length of the segment.

To determine the magnetic field's magnitude, the enclosed current within the trajectory needs to be calculated. This involves defining the concept of spiral density as the ratio of the number of spirals to the length of the solenoid.

In a toroid, circular currents generate a magnetic field where the field lines curve and form closed loops. This principle is utilized in devices like particle accelerators.

The magnetic field in a toroid varies in different zones. In the central zone, where no current crosses the circumference, there is no magnetic field. In the interior zone, the enclosed current is determined by the number of spirals passing through the circumference.

The density of turns in a toroid affects the magnetic field inside. When the difference between the inner and outer radii of the toroid is small, the magnetic field inside can be approximated to that of a solenoid. In the external zone, the magnetic field is pure due to the cancellation of incoming and outgoing trajectories. Transformers, crucial in electrical systems, use two solenoids around a common iron core to increase or decrease AC voltage without altering power.

Transformers consist of two solenoids wound around an iron core, isolating the primary and secondary circuits. The primary circuit carries current inducing a magnetic field in the first coil, channeled by the iron core to the second coil. The iron core, a ferromagnetic material with magnetic domains, directs the magnetic field, inducing a current in the secondary circuit based on the transformer's turns ratio.

In transformers, a variable magnetic field induces an electromotive force and current in the secondary circuit based on the turns ratio between primary and secondary coils. The relationship between the number of turns in the primary and secondary coils determines the variations in induced intensity and voltage. Further discussions on induction are left for future videos.

The video concludes with a thank you message to viewers for choosing the channel to learn. Viewers are encouraged to ask questions in the comments or via email for resolving exercises. Subscriptions are welcomed, and the importance of continuous learning is emphasized. The video ends with a reminder that knowledge never goes out of style.