The magnetic field is homogeneous and inhomogeneous: the characteristic and definition

One of the basic concepts used in physics is the magnetic field. It affects the moving electric charges. Insensible and not felt by a person, but its presence can be detected with a magnet or iron. It is also quite easy to understand which magnetic field is called homogeneous and inhomogeneous.

Determination and methods for detecting a magnetic field

When we come across the concept of a magnetic field, we are faced with the question of whether this magnetic field is homogeneous or inhomogeneous. Before answering such a question, it is necessary to give initial definitions to terms.

A magnetic field is supposed to be considered a special kind of matter existing near moving electric charges, especially near conductors with current. You can detect using a magnetic needle or iron filings.

Homogeneous field

Occurs inside the strip magnet and in the solenoid, when its length is much larger than the diameter. In this case, according to the rule of the borer, the contours of the magnetic field will be directed counterclockwise.

Magnetic lines are parallel and straight, the emptiness between them is always the same, the force of influence on the magnetic needle does not differ at all points in its magnitude and direction.

Nonhomogeneous field

In the case of an inhomogeneous field, the magnetic lines will bend, the void between them will vary in magnitude, the force of the action on the magnetic needle will differ in different points of the field in magnitude and direction. Also, the force acting on the arrow placed in the field of the strip magnet acts at different points with forces of different modulus and direction. This is called an inhomogeneous field. The lines of this field are curved, the frequency varies from point to point.

It is possible to detect such a field near a direct conductor with a current, a strip magnet and a solenoid.

What are magnetic lines?

First of all, when the problem arises, it is necessary to determine which magnetic field, homogeneous or non-uniform, is formed, it is necessary to learn about the magnetic lines, in the form of which the field characteristic becomes clear.

To represent the magnetic field, magnetic lines began to be used. They are imaginary bands located along the magnetic needle and placed in a magnetic field. It is possible to draw a magnetic line through any point of the field, it will have a direction and always close.

Direction

They exit from the north pole of the magnet and are sent to the south pole. From the inside of the magnet itself, everything is strictly opposite. The lines themselves do not have a beginning or an end, they are closed or pass from infinity to infinity.

Outside the magnet lines are located most densely near the poles. From this it becomes clear that the field is most strongly affected near the poles, and as it moves away from the bottom, it weakens. Given that the magnetic strips are twisted, the direction of the force that acts on the magnetic needle also changes.

How to Draw

To understand how homogeneous magnetic fields differ from inhomogeneous ones, it is necessary to learn how to represent them using magnetic lines.

We should consider the above example of the appearance of a homogeneous magnetic field in the so-called solenoid, which is a wire cylindrical coil, through which a current is started. Inside, the magnetic field can be considered homogeneous, provided that the length is much larger than the diameter (outside the coil the field will be non-uniform, the magnetic lines will be located in the same way as in the strip magnet).

A homogeneous field is also located in the center of a permanent strip magnet. In a limited area in space, it is possible to reproduce a homogeneous magnetic field in which the forces of action on the magnetized arrow will be the same in magnitude and direction.

To depict the magnetic field, use the following example. If the lines are located perpendicular to the drawing plane and are directed from the viewer, then they are represented by crosses, if the viewer points - by points. As with current, each cross is like a visible tail feather flying from the looking arrow, and the point is sharper than the arrow that flies towards us.

Also, the requirement "Draw a homogeneous and inhomogeneous magnetic field" is easily feasible. Simply draw these magnetic lines, taking into account the characteristics of the field (homogeneity and heterogeneity).

However, the existence of inhomogeneous fields greatly complicates the problem. In this case, obtaining a physical result using the general equation is unlikely.

Differences

The answer to the question of how homogeneous magnetic fields differ from inhomogeneous magnetic fields is fairly easy to give. First of all, it depends on the magnetic lines. In the case of a homogeneous field, the distance between them will be the same, and they will be uniformly distributed, with the same force acting on the devices at any point. For heterogeneous fields, everything is strictly opposite. The lines are unevenly distributed, in different places they operate with unequal force on the instruments.

In practice, a heterogeneous field is often encountered, which should also be remembered, since homogeneous fields can occur only inside an object, such as a magnet or a solenoid. External observations, however, fix heterogeneity.

Field Detection

Having understood what such homogeneous and inhomogeneous magnetic fields are, and their definitions are analyzed, it is necessary to find out in what way it is possible to detect them.

The most simple for this is the experience conducted by Oersted. It consists in the use of a magnetic needle, which helps determine the existence of an electric current. As soon as the current moves along the conductor, the arrow next to it will move, due to the fact that there are homogeneous and inhomogeneous magnetic fields.

Interaction of conductors with a current

Each conductor with a current observes its own magnetic field, acting with a certain force on the nearest one. Depending on the direction of the current, the conductors will be attracted or repelled from each other. Fields originating from different sources will add up and form a single resulting field.

How are they created and for what?

Examples of a homogeneous and inhomogeneous magnetic field used in electron beam devices are created by coils that pass current. To obtain the desired shape of the magnetic field, we use laths and magnetic screens made of materials with a strong magnetic permeability.

The influence of inhomogeneous magnetic fields can change the course of irreversible phenomena of a physico-chemical nature, mainly a heterogeneous process. The appearance of turbulent diffusion leads to an increase by several orders of magnitude of the rate of movement of gas from any liquid to the surface in the form of microbubbles. The effect of local dehydration of ions and particles is due to the intensification of the microcrystallization process. In flowing media, high-energy reactions can create free radicals, atomic oxygen, peroxides and nitrogenous compounds. There is coagulation, and in the liquid are products caused by erosion destruction.

During hydrodynamic cavitation, a large amount of emerging bubbles and caverns complicates their removal by liquid from the area of reduced pressure to the zone of higher pressure, where bubbles are collapsed. During the collapse of a small bubble there is a small amount of air and a strong chemical reaction occurs, similar to a plasma discharge. The presence of inhomogeneous magnetic fields leads to unstable caverns, their decay and the appearance of small-scale eddies and bubbles. Considering that the pressure in the center of such a vortex is lowered, it converts gas bubbles of small size.

When measuring induction in an inhomogeneous magnetic field, it should be remembered that the Hall voltage is proportional to the average field induction value within the area bounded by the surface of the transducer.

In order to focus the paraxial beams, inhomogeneous magnetic fields formed by short coils, which are multilayer solenoids, whose length is commensurate with their diameter, are also used. On an electron falling into such a field, there are forces that change its direction. An electron under the influence of such a force approaches the axis of the lens, and the plane in which its trajectory is located is curved. The electron moves along a spiral section that intersects the axis of the lens at a given point.

The spatial factor of the increase is caused by the spatial dispersion of the inhomogeneous fields in the territory of a heterogeneous system, a liquid with a wipe. To obtain a population inversion of the levels by the separation method, inhomogeneous fields created by a multiband magnet are used. The shape of the poles is similar to the rods in the quadrupole capacitor of a molecular generator on ammonia.

Ways to use

The magnetic-order method of flaw detection is based on the pull of magnetic particles by the forces of inhomogeneous fields appearing above the defects. By accumulation of such a powder, the presence of the defect, its magnitude and position on the inspected part is clarified.

An important disadvantage of the method of molecular beams with the use of strong inhomogeneous magnetic fields is the small splitting effect. There is a simple and seemingly implausible method of increasing this effect. It consists in the application of a light external magnetic field. The latter will make it possible to increase the use of nuclear precession magnetometers in the direction of inhomogeneous magnetic fields.

The advantage of this method is high resolution, which makes it possible to fix inhomogeneous magnetic fields commensurate with the value of the particles of the magnetic layer of the tape, as well as the possibility of finding damage on complex surfaces and in close openings.

The disadvantages are the need for secondary processing of information, only the particles of magnetic fields along the tape are fixed, the demagnetization and tape conservation are difficult, and it is necessary to prevent the influence of external magnetic fields.

The magnetic field is homogeneous and heterogeneous occur quite often, despite the fact that they are invisible to the common man in the street. Examples of a homogeneous and inhomogeneous magnetic field can be found in band magnets and solenoids. In this case, you can notice them using a simple magnetic needle or iron filings.