Electricity is a rather complex branch of physics, it is full of various laws and phenomena that accompany the flow of current in a conductor. For example, if we have two or more conductors through which an electric current flows, then the conductors will attract or repel each other. This is a manifestation of Ampere's strength. In this article, we will explain in simple language what this phenomenon is and where it is applied.
Content:
- Definition
- Ampere force direction
- Application in practice
Definition
Ampere's law states that the force that arises around a conductor is directly proportional to its length, current strength and magnetic induction, as well as the cosine of the angle between the conductor and the magnetic vector induction. Accordingly, its formula:
F = BILcosa
This F is the Ampere force. Doesn't it look like anything? Both the formula and its very physical meaning are similar Lorentz force. The only difference is that Ampere's law is valid for a conductor in a magnetic field, and Lorentz acts on charged particles.
If we represent it in vector form, then the equation will look like:
And in differential form:
There is another formulation: Ampere's law characterizes the force acting on a conductor in a magnetic field. It was discovered by André Marie Ampere in 1820.
How is Ampere's strength measured? As well as other forces in physics - in Newtons (N).
Interesting! In domestic physics, in most cases, the SI system of units is adhered to. So in this system, the value of 1 Ampere is understood as such a current, when flowing through two conductors located in parallel and 1 meter apart, there would be an interaction force in 2 * 10 ^ (- 7) N. Moreover, they have an infinite length, a minimum cross-sectional area and are located in a vacuum.
Since this law implies the emergence of some kind of force, there is no doubt that in the presence of several such forces, they will interact with each other. Let's figure out exactly how.
When parallel currents flow in the same direction interact, two adjacent conductors will begin to attract. If the currents flow in different directions, the conductors will repel. This is the most important action in this law.
Ampere force direction
The left hand rule is used to determine the direction of these forces. To do this, place the open palm of the left hand near the conductor so that lines of the magnetic induction vector, and four open fingers indicated the direction of flow current. Then the thumb bent at a right angle will indicate the direction of the force of Ampere and Lorentz.
Recall that the direction of the magnetic induction vector is determined using the right-hand rule. To do this, you need to go around four fingers of your right hand around the conductor, bend your thumb at a right angle (as if you are showing a "class"), so that it indicates the direction of the current. Then four bent fingers will show how the lines of the magnetic field pass, they will describe circles around the conductive core.
Application in practice
Ampere's law is one of the most important laws in electrical engineering. Let's take a look at examples from its practical application. The basis of almost any enterprise is the electric drive. Motor and electromagnetic actuators are used to move or actuate various components:
- automated gate valves for pipelines;
- lifting mechanisms;
- electric transport (electric locomotives on the railway);
- trams;
- trolleybuses;
- electric cars and so on.
Ampere force causes the motor to rotate due to the interaction between the rotor and stator windings. In order for the windings to rotate, they are either switched using a brush assembly and a collector in DC motors, or using alternating current.
Ampere's law has also found its way into speakers and loudspeakers. There, the membrane moves, on which a copper wire winding is located in the magnetic field of a permanent magnet.
Its action is observed during short circuits on power lines. Where, under the influence of ultra-high currents, tires and wires begin to bend.
At the moment of firing from the railgun, the rails move apart. This is due to the reasons already listed.
Finally, we recommend watching a useful video on the topic:
All phenomena in electricity are important, some have less impact, some more. However, to understand where and how they manifest themselves should be everyone who is associated with this area, regardless of an electrician, an automated control system engineer or an instructor. We hope you now know what Ampere's Law describes, as well as its practical significance!
Related materials:
- Joule-Lenz law
- How to convert amperes to kilowatts
- Distribution of charges in a conductor
