What is the drill rule?

For someone who has chosen electrical engineering as their main profession, some of the basic properties of the electric current and the associated magnetic fields are very well known. One of the most important of these is the rule of the gimlet. On the one hand, it is rather difficult to call this rule law. It is more correct to say that this is one of the fundamental properties of electromagnetism.

What is the drill rule? Definition, although it exists, but for a more complete understanding it is worth remembering the basics of electricity. As is known even from the school course of physics, the electric current is the movement of elementary particles carrying an electric charge on some conductive material. Usually it is compared with the interatomic motion of valence electrons, which, due to external action (for example, a magnetic pulse), receive a portion of energy sufficient to leave their steady orbit in the atom. Let's conduct a mental experiment. For this we need the load, source of EMF and conductor (wire), which connects all the elements into a single closed circuit.

The source creates a directional motion of elementary particles in the conductor. At the same time, as early as the 19th century, it was observed that around such a conductor a magnetic field appeared that rotated in one direction or another. The rule of the borer can be used to determine the direction of rotation. The spatial configuration of the field is a kind of tube, in the center of which the conductor is located. It would seem: what a difference, how this generated magnetic field behaves! However, even Amper pointed out that two conductors with current act on each other with their magnetic fields, repelling or attracting each other, depending on the direction of rotation of their fields. Later, on the basis of a series of experiments, Ampere formulated and substantiated his law of interaction (by the way, he underlies the work of electric motors). Obviously, without knowing the rule of the drill, it is very difficult to understand the processes that are taking place.

In our example , the current direction is known - from "+" to "-". Knowing the direction makes it easy to use the rule of the gimlet. Mentally, we begin to screw the right-hand bore-hole in the conductor (along it) so that the resulting translational movement is co-axial with the current flow direction. In this case, the rotation of the handle will coincide with the rotation of the magnetic field. You can use another example: screw the usual screw (bolt, screw).

This rule can be used a little differently (although the basic meaning is the same): if you mentally wrap your right hand with a current conductor so that four bent fingers indicate the direction in which the field rotates, then the bent thumb will indicate the direction of the current flowing through the conductor . Accordingly, the converse is also true: knowing the direction of the current, "wrapping" the wire, one can know the direction of the rotation vector of the created magnetic field. This rule is actively used in calculations of coils of inductance, in which, depending on the direction of the turns, it is possible to influence the flowing current (creating, if necessary, a counterflow).

The driller law allows us to formulate a consequence: if the right hand is placed in such a way that the lines of tension of the generated magnetic field enter into it, and four straightened fingers point to the known direction of motion of the charged particles in the conductor, the thumb bent at 90 degrees will indicate the direction of the vector Force, which exerts a bias on the conductor. By the way, this force creates a torque on the shaft of any electric motor.

Apparently, there are a lot of ways to use the above rule, so the main "difficulty" is to select each person that is understandable to him.