View of the magnetic field
We all know what permanent magnets are. Magnets are metal bodies that are attracted to other magnets and to some metals. That which is located around the magnet and interacts with the surrounding objects (attracts or repels some of them) is called a magnetic field.
The source of any magnetic field are moving charged particles. And the directed movement of charged particles is called electric current. That is, any magnetic field is caused exclusively by electric current.
For the direction of the electric current take the direction of movement of positively charged particles. If negative charges move, the direction of the current is assumed to be the reverse of the movement of such charges. Imagine that water flows through a circular pipe. But we will assume that a certain “current” moves in the opposite direction. Electric current is denoted by the letter I.
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In metals, the current is formed by the movement of electrons - negatively charged particles. In the figure below, the electrons move along the conductor from right to left. But it is believed that the electric current is directed from left to right.
This happened because when the study of electrical phenomena began, it was not known which carriers most often carried the current.
If we look at this conductor from the left side, so that the current flows "from us", then the magnetic field of this current will be directed around it clockwise.
If a compass is positioned next to this conductor, then its arrow will unfold perpendicular to the conductor, parallel to the “magnetic field lines of force” - parallel to the black circular arrow in the figure.
If we take a ball that has a positive charge (having a deficit of electrons) and throw it forward, then exactly the same ring magnetic field will appear around this ball, spinning around it in a clockwise direction.
After all, there is also a directional movement of the charge. And the directed movement of charges is an electric current. If there is a current, there should be a magnetic field around it.
A moving charge (or a set of charges - in the case of an electric current in a conductor) creates around itself a “tunnel” of a magnetic field. The walls of this "tunnel" "denser" near the driving charge. The farther away from a moving charge, the weaker the intensity (“force”) of the magnetic field created by it. The weaker the compass needle responds to this field.
The pattern of distribution of the magnetic field around its source is the same as the pattern of distribution of the electric field around a charged body - it is inversely proportional to the square of the distance to the field source.
If a positively charged ball moves in a circle, then the rings of the magnetic fields generated around it as it moves, are summed, and we get a magnetic field directed perpendicular to the plane in which the charge moves:
The magnetic “tunnel” around the charge turns into a ring and resembles a torus (bagel) in shape.
The same effect is obtained if you roll a current-carrying conductor into a ring. Conductor with current, rolled into a multi-turn coil is called an electromagnet. Around the coil are the magnetic fields of the charged particles moving in it - electrons.
And if the charged ball is rotated around its axis, then it will have a magnetic field, like that of the Earth, directed along the axis of rotation. In this case, the current causing the appearance of a magnetic field is a circular movement of a charge around the axis of the ball - a circular electric current.
Here, in essence, the same thing happens as when the ball moves in a circular orbit. Only the radius of this orbit is reduced to the radius of the ball itself.
All the above is true for a negatively charged ball, but its magnetic field will be directed in the opposite direction.
This effect was found in the experiments of Rowland and Eichenwald. These gentlemen registered magnetic fields near rotating charged disks: a compass needle began to deviate next to these disks. The directions of the magnetic fields, depending on the sign of the charge of the disks and the direction of their rotation, are shown in the figure:
When rotating an uncharged disk, no magnetic fields were detected. There were no magnetic fields near stationary charged disks.
To remember the direction of the magnetic field of a moving positive charge, we will imagine ourselves in its place. Raise the right hand up, then point it to the right, then move it down, then point left and return the hand to its original position - up. Then we repeat this movement. Our hand describes circles in a clockwise direction. Now we will start moving forward, continuing to rotate the hand. The movement of our body is an analogue of the movement of a positive charge, and the rotation of the hand clockwise is an analogue of the magnetic field of a charge.
Now imagine that around us there is a thin and durable elastic web, similar to the strings of space that we drew, creating a model of the electric field.
When we move through this three-dimensional "web", because of the rotation of the hand, it, being deformed, moves clockwise, forming a kind of spiral, as if winding around a charge in a coil.
Behind us, the "web" is rebuilding its proper structure. Something like this you can imagine the magnetic field of a positive charge, moving directly.
And now try to move not straight ahead, but in a circle, for example, turning while walking to the left, at the same time turning your hand clockwise. Imagine that you are moving through something resembling jelly. Because of the rotation of your hand, inside the circle in which you move, the “jelly” will move upwards, forming a hump above the center of the circle. And under the center of the circle, a depression is formed due to the fact that part of the jelly has shifted upwards. So you can imagine the formation of the north (hump on top) and south (bottom depression) poles when the charge moves along the ring or its rotation.
If, when walking, you turn right, the "hump" (north pole) will form at the bottom.
Similarly, one can form an idea of ​​the magnetic field of a moving negative charge. Only need to rotate the hand in the opposite direction - counterclockwise. Accordingly, the magnetic field will be directed in the opposite direction. Just watch each time in which direction your hand pushes the jelly.
Such a model clearly demonstrates why the north pole of one magnet is attracted to the south pole of another magnet: the “hump” of one of the magnets retracts into the “hollow” of the second magnet.
And this model shows why there are no separate north and south poles of magnets, no matter how we cut them - the magnetic field is a vortex (closed) "deformation of space" around the trajectory of a moving charge.
The electron was found to have a magnetic field, such as it should have if it were a ball, rotating around its axis. This magnetic field was called spin (from English to spin - to rotate).
In addition, the electron also has an orbital magnetic moment. After all, an electron not only "rotates", but moves in orbit around the nucleus of an atom. And the movement of a charged body generates a magnetic field. Since the electron is negatively charged, the magnetic field caused by its orbital motion will look like this:
If the direction of the magnetic field caused by the movement of an electron in an orbit coincides with the direction of the magnetic field of the electron itself (its spin), these fields are added and strengthened. If these magnetic fields are directed in different directions, they are subtracted and weaken each other.
In addition, magnetic fields of other electrons of an atom can be summed up or subtracted from each other. This explains the presence or absence of magnetism (reaction to an external magnetic field or the presence of an intrinsic magnetic field) of certain substances.
This article is an excerpt from a book about the basics of chemistry. The book itself is here:
sites.google.com/site/kontrudar13/himia
The source of any magnetic field are moving charged particles. And the directed movement of charged particles is called electric current. That is, any magnetic field is caused exclusively by electric current.
For the direction of the electric current take the direction of movement of positively charged particles. If negative charges move, the direction of the current is assumed to be the reverse of the movement of such charges. Imagine that water flows through a circular pipe. But we will assume that a certain “current” moves in the opposite direction. Electric current is denoted by the letter I.
')
In metals, the current is formed by the movement of electrons - negatively charged particles. In the figure below, the electrons move along the conductor from right to left. But it is believed that the electric current is directed from left to right.
This happened because when the study of electrical phenomena began, it was not known which carriers most often carried the current.
If we look at this conductor from the left side, so that the current flows "from us", then the magnetic field of this current will be directed around it clockwise.
If a compass is positioned next to this conductor, then its arrow will unfold perpendicular to the conductor, parallel to the “magnetic field lines of force” - parallel to the black circular arrow in the figure.
If we take a ball that has a positive charge (having a deficit of electrons) and throw it forward, then exactly the same ring magnetic field will appear around this ball, spinning around it in a clockwise direction.
After all, there is also a directional movement of the charge. And the directed movement of charges is an electric current. If there is a current, there should be a magnetic field around it.
A moving charge (or a set of charges - in the case of an electric current in a conductor) creates around itself a “tunnel” of a magnetic field. The walls of this "tunnel" "denser" near the driving charge. The farther away from a moving charge, the weaker the intensity (“force”) of the magnetic field created by it. The weaker the compass needle responds to this field.
The pattern of distribution of the magnetic field around its source is the same as the pattern of distribution of the electric field around a charged body - it is inversely proportional to the square of the distance to the field source.
If a positively charged ball moves in a circle, then the rings of the magnetic fields generated around it as it moves, are summed, and we get a magnetic field directed perpendicular to the plane in which the charge moves:
The magnetic “tunnel” around the charge turns into a ring and resembles a torus (bagel) in shape.
The same effect is obtained if you roll a current-carrying conductor into a ring. Conductor with current, rolled into a multi-turn coil is called an electromagnet. Around the coil are the magnetic fields of the charged particles moving in it - electrons.
And if the charged ball is rotated around its axis, then it will have a magnetic field, like that of the Earth, directed along the axis of rotation. In this case, the current causing the appearance of a magnetic field is a circular movement of a charge around the axis of the ball - a circular electric current.
Here, in essence, the same thing happens as when the ball moves in a circular orbit. Only the radius of this orbit is reduced to the radius of the ball itself.
All the above is true for a negatively charged ball, but its magnetic field will be directed in the opposite direction.
This effect was found in the experiments of Rowland and Eichenwald. These gentlemen registered magnetic fields near rotating charged disks: a compass needle began to deviate next to these disks. The directions of the magnetic fields, depending on the sign of the charge of the disks and the direction of their rotation, are shown in the figure:
When rotating an uncharged disk, no magnetic fields were detected. There were no magnetic fields near stationary charged disks.
Model of the magnetic field of a moving charge
To remember the direction of the magnetic field of a moving positive charge, we will imagine ourselves in its place. Raise the right hand up, then point it to the right, then move it down, then point left and return the hand to its original position - up. Then we repeat this movement. Our hand describes circles in a clockwise direction. Now we will start moving forward, continuing to rotate the hand. The movement of our body is an analogue of the movement of a positive charge, and the rotation of the hand clockwise is an analogue of the magnetic field of a charge.
Now imagine that around us there is a thin and durable elastic web, similar to the strings of space that we drew, creating a model of the electric field.
When we move through this three-dimensional "web", because of the rotation of the hand, it, being deformed, moves clockwise, forming a kind of spiral, as if winding around a charge in a coil.
Behind us, the "web" is rebuilding its proper structure. Something like this you can imagine the magnetic field of a positive charge, moving directly.
And now try to move not straight ahead, but in a circle, for example, turning while walking to the left, at the same time turning your hand clockwise. Imagine that you are moving through something resembling jelly. Because of the rotation of your hand, inside the circle in which you move, the “jelly” will move upwards, forming a hump above the center of the circle. And under the center of the circle, a depression is formed due to the fact that part of the jelly has shifted upwards. So you can imagine the formation of the north (hump on top) and south (bottom depression) poles when the charge moves along the ring or its rotation.
If, when walking, you turn right, the "hump" (north pole) will form at the bottom.
Similarly, one can form an idea of ​​the magnetic field of a moving negative charge. Only need to rotate the hand in the opposite direction - counterclockwise. Accordingly, the magnetic field will be directed in the opposite direction. Just watch each time in which direction your hand pushes the jelly.
Such a model clearly demonstrates why the north pole of one magnet is attracted to the south pole of another magnet: the “hump” of one of the magnets retracts into the “hollow” of the second magnet.
And this model shows why there are no separate north and south poles of magnets, no matter how we cut them - the magnetic field is a vortex (closed) "deformation of space" around the trajectory of a moving charge.
Spin
The electron was found to have a magnetic field, such as it should have if it were a ball, rotating around its axis. This magnetic field was called spin (from English to spin - to rotate).
In addition, the electron also has an orbital magnetic moment. After all, an electron not only "rotates", but moves in orbit around the nucleus of an atom. And the movement of a charged body generates a magnetic field. Since the electron is negatively charged, the magnetic field caused by its orbital motion will look like this:
If the direction of the magnetic field caused by the movement of an electron in an orbit coincides with the direction of the magnetic field of the electron itself (its spin), these fields are added and strengthened. If these magnetic fields are directed in different directions, they are subtracted and weaken each other.
In addition, magnetic fields of other electrons of an atom can be summed up or subtracted from each other. This explains the presence or absence of magnetism (reaction to an external magnetic field or the presence of an intrinsic magnetic field) of certain substances.
This article is an excerpt from a book about the basics of chemistry. The book itself is here:
sites.google.com/site/kontrudar13/himia
Source: https://habr.com/ru/post/444790/
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