In 1820, the distinguished French physicist AndreMarie Amper (it is in his honor called the unit of measurement of electric current) formulated one of the fundamental laws of all electrical engineering. Subsequently, this law was named the power of the ampere.
As is known, when passing through a conductorelectric current around it there is its own (secondary) magnetic field, the lines of tension of which form a kind of rotating shell. The direction of these lines of magnetic induction is determined with the help of the rule of the right hand (the second name is the "drill rule"): we mentally wrap the conductor with the right hand so that the flow of charged particles coincides with the direction indicated by the bent thumb. As a result, the other four fingers, wrapping the wire, will indicate the rotation of the field.
If one places two such conductors parallel(thin wires), then the interaction of their magnetic fields will be affected by the ampere force. Depending on the direction of the current in each conductor, they can repel or attract. At currents flowing in one direction, the ampere force exerts an attractive effect on them. Accordingly, the opposite direction of the currents causes repulsion. This is not surprising: although similar charges repel, in this example, not the charges themselves interact, but magnetic fields. Since the direction of their rotation is the same, the resulting field is a vector sum, not a difference.
In other words, the magnetic field affects a conductor that crosses tension lines in a certain way. The power of an ampere (an arbitrary shape of a conductor) is determined from the law formula:
dF = B * I * L * sin a;
where - I - value of current strength in the conductor; B -Induction of the magnetic field in which the conductive material is placed; L - taken for the calculation of the length of the conductor with current (moreover, in this case it is assumed that the length of the conductor and the force tend to zero); alpha (a) is the vector angle between the direction of motion of the charged elementary particles and the lines of the strength of the external field. The corollary is the following: when the angle between the vectors is 90 degrees its sin = 1, and the value of the force is maximized.
The vector direction of the action of the ampere forcedetermine by the rule of the left hand: mentally place the palm of the left hand in such a way that the lines (vectors) of the magnetic induction of the external field enter the open palm, and the remaining four straightened fingers indicate the direction in which the current flows in the conductor. Then the thumb, bent at an angle of 90 degrees, will show the direction of the force acting on the conductor. If the angle between the electric current vector and an arbitrary induction line is too small, then to simplify the application of the rule, the palm of the hand should not include the induction vector, but the modulus.
The use of ampere power has made it possible to createelectric motors. We are all accustomed to having enough to click the switch of an electric household appliance equipped with a motor so that its actuator comes into action. And about the processes occurring in this case, no one really thinks about it. The direction of the ampere force not only explains the principle of the engines, but also allows you to determine exactly where the torque will be directed.
For example, imagine a DC motor:its anchor is a frame-base with a winding. An external magnetic field is created by special poles. Since the winding wound around the anchor is circular, then the direction of the current on the sections of the conductor is opposite from opposite sides of it. Consequently, the vectors of action of the ampere force are also encountered. Since the armature is fixed to the bearings, the mutual action of the ampere force vectors creates a torque. As the current value increases, the force also increases. That is why the nominal electric current (indicated in the electrical equipment certificate) and the torque are directly interrelated. The increase in current is limited by the design features: the cross-section of the wire used for the winding, the number of turns,
