Rule of gimbal, right hand and left hand have found wide application in physics. Mnemonic rules are needed for easy and intuitive memorization of information. Usually this is an application of complex quantities and concepts to household and improvised things. The first to formulate these rules is the physicist Pyotr Buravchik. This rule refers to the mnemonic and is closely related to the rule of the right hand, its task is to determine the direction of axial vectors for a known direction of the basic one. This is what the encyclopedias say, but we will tell you about it in simple words, briefly and clearly.
Content:
- Explanation of the name
- How the magnetic field is connected with the gimbal and hands
- Magnetic field in the solenoid
- Determination of the direction of the current with a gimbal
- What has to do with the left hand
- conclusions
Explanation of the name
Most people remember the mention of this from the physics course, namely the electrodynamics section. It happened for a reason, because this mnemonic is often given to students to simplify the understanding of the material. In fact, the gimbal rule is used both in electricity, to determine the direction of the magnetic field, and in other sections, for example, to determine the angular velocity.
A gimbal means a tool for drilling small-diameter holes in soft materials; for a modern person, it will be more common to give a corkscrew as an example.
Important! It is assumed that the gimlet, screw or corkscrew has a right-hand thread, that is, the direction of its rotation, when screwed, is clockwise, i.e. to the right.
The video below provides the full wording of the gimbal rule, be sure to look to understand the whole point:
How the magnetic field is connected with the gimbal and hands
In physics problems, in the study of electrical quantities, they are often faced with the need to find the direction of the current, according to the vector of magnetic induction and vice versa. Also, these skills will be required when solving complex problems and calculations related to the magnetic field of systems.
Before proceeding with the consideration of the rules, I want to remind you that the current flows from a point with a high potential to a point with a smaller one. It can be said more simply - the current flows from plus to minus.
The gimbal rule has the following meaning: when the gimbal tip is screwed along the direction of the current, the handle will rotate in the direction of the vector B (the vector of the magnetic induction lines).
The right hand rule works like this:
Place your thumb as if you are showing "class!", Then turn your hand so that the direction of the current and the finger coincide. Then the remaining four fingers will coincide with the magnetic field vector.
A clear breakdown of the right-hand rule:
To see this more clearly, conduct an experiment - sprinkle metal shavings on paper, make in a sheet hole and thread the wire, after applying current to it, you will see that the chips are grouped into concentric circles.
Magnetic field in the solenoid
All of the above is true for a straight conductor, but what if the conductor is wound into a coil?
We already know that when current flows around a conductor, a magnetic field is created, a coil is a wire coiled into rings around a core or mandrel many times. In this case, the magnetic field is amplified. Solenoid and coil are basically the same thing. The main feature is that the magnetic field lines run in the same way as in the situation with a permanent magnet. The solenoid is a controlled analogue of the latter.
The right hand rule for a solenoid (coil) will help us determine the direction of the magnetic field. If you hold the coil in your hand so that four fingers are facing in the direction of the current flow, then your thumb will point to vector B in the middle of the coil.
If you twist the gimbal along the turns, again in the direction of the current, i.e. from the "+" terminal to the "-" terminal of the solenoid, then the sharp end and direction of movement are the same as the magnetic induction vector.
In simple words, where you turn the gimbal, the magnetic field lines go out there. The same is true for one turn (circular conductor)
Determination of the direction of the current with a gimbal
If you know the direction of the vector B - magnetic induction, you can easily apply this rule. Mentally move the thumb along the direction of the field in the coil with the sharp part forward, respectively, clockwise rotation along the axis of movement will show where the current flows.
If the wire is straight, rotate the corkscrew along the indicated vector so that this movement is clockwise. Knowing that it has a right-hand thread - the direction in which it is screwed in coincides with the current.
What has to do with the left hand
Do not confuse the gimbal and the left hand rule, it is needed to determine the force acting on the conductor. The straightened palm of the left hand is positioned along the guide. The fingers point in the direction of the current I. The lines of the field pass through the open palm. The thumb coincides with the force vector - this is the meaning of the left hand rule. This force is called the Ampere force.
You can apply this rule to an individual charged particle and determine the direction of 2 forces:
- Lorenz.
- Ampere.
Imagine a positively charged particle moving in a magnetic field. The lines of the magnetic induction vector are perpendicular to the direction of its movement. You need to put your open left palm with your fingers in the direction of the charge movement, vector B should penetrate the palm, then the thumb will indicate the direction of vector Fа. If the particle is negative, the fingers are facing against the charge path.
If at some point you did not understand, the video clearly shows how to use the left-hand rule:
It's important to know! If you have a body and a force acts on it that tends to turn it, turn the screw in this direction, and you will determine where the moment of force is directed. If we talk about angular velocity, then the situation is as follows: when the corkscrew rotates in one direction with the rotation of the body, it will screw in the direction of the angular velocity.
conclusions
It is very easy to master these methods of determining the direction of forces and fields. Such mnemonic rules in electricity greatly facilitate the tasks of schoolchildren and students. Even a full teapot can handle the gimbal if he has opened the wine with a corkscrew at least once. The main thing is not to forget where the current flows. I repeat that the use of the gimbal and the right hand is most often successfully used in electrical engineering.
Finally, we recommend watching the video, thanks to which you can understand by example what the gimbal rule is and how to apply it in practice:
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