Electrotechnics: Basics


Electric field lines

The magnitude or intensity of the electric field in the space surrounding the charge, which is the source, in direct proportion to the amount of this charge and the inverse square of the distance from that charge. Direction the electric field according to the accepted rules of the always positive charge to a negative charge. It can be seen as if to put the probe charge in the region of space electric field source and the the probe charge would be either repelled or attracted (depending on the sign of the charge). The electric field is characterized by a voltage which is a vector quantity can be represented graphically in the form of an arrow having a length and a direction. Anywhere in the direction of the arrow indicates the direction the electric field intensity E, or simply - the direction of the field, and the length of the arrow is proportional to the numerical value the electric field intensity at this point. The farther away a region of space from the field source (charge Q), the smaller the length of the vector of tension. Moreover, the vector length decreases with distance n times from a certain place in the n2 times, that is inversely proportional to the square.

A more useful tool for visual representation of the vector nature of the electric field is the use of such concepts as the electric field lines, or just - power lines. Instead of portraying countless vector arrows in the space surrounding the charge-source proved useful to combine them into a line where the vectors themselves are tangent to the points on these lines.

In the end, a success for the presentation vector pattern of the electric field applied electric field lines that go from the positive charge sign and enter the negative sign of the charges, as well as extend to infinity in space. This representation allows the mind to see the invisible to the human eye the electric field. However, this view is also convenient for the gravitational forces, and any other non-contact long-range interactions.

Field lines of solitary charges

Model electric field lines includes an infinite number of them, but too high a density of the image lines of force reduces the possibility of reading the patterns of the field, so their number is limited readability.

Rules of drawing electric field lines

There are plenty of rules for the preparation of models of electric field lines. All these rules are designed to inform the most informative when rendering (drawing) of the electric field. One method - the image of the lines of force. One of the most common ways - it is surrounded by a large number of charged objects lines, that is, higher density lines. Objects with a big charge creates a strong electric field, and therefore the density (thickness) of the lines around them more. The closer to the source of the charge, the higher the density of lines of force, and the greater the amount of charge around the thicker line.

The second rule for drawing lines of the electric field includes the image lines of a different type such that intersect the first lines of force perpendicularly. This type of line is called equipotential lines, and a volume representation should speak of equipotential surfaces. This type of lines form a loop and every point on such a equipotential line has the same value of the potential field. When a charged particle crosses any such lines of force perpendicular line (the surface), it is said to commit the charge of the work. If the charge will move along the equipotential lines (surfaces), that although he is moving, but at the same time no work not performed. A charged particle, being in the electric field of another charge starts to move, but in the static electricity charges are only considered fixed. The movement of charges is called electric current, and the charge carriers can commit work.

It is important to remember that the electric field lines do not intersect, and the lines of another type - equipotential form a closed loop. At the point where there is a crossing of two types of lines tangent to these lines are mutually perpendicular. Thus it turns out something like a curved grid or lattice whose cells, as well as the point of intersection of the lines of different types characterized by an electric field.

Force and potential lines

Electric field created by two or more charge

For a solitary individual charges the electric field lines are radial rays coming from the charges and going to infinity. What will be the configuration of the field lines for two or more of the charges? To accomplish this pattern must be remembered that we are dealing with the vector field, ie with the electric field vector. To portray the image of the field, we need to perform the addition of the vectors of two or more charges. The resulting vector will be a total field of several charges. As in this case it is possible to construct a power line? It is important to remember that each point on the power line - this is the only point of contact with the vector of the electric field. This follows from the definition of tangent geometry. If from the beginning of each vector perpendicular to build in long lines, then the mutual intersection of many of these lines will represent the most desired power line.

For a more accurate mathematical algebraic image of lines of force necessary to make the equation of power lines, and the vector in this case, will represent the first derivatives of the first order line that is tangent. This problem is often extremely complex and require computing.

First of all it is important to remember that the electric field from the charge represented by the sum of many vectors of each source charge. This is the basis for the implementation of the construction of power lines in order to visualize the electric field.

Each entered in charge of the electric field leads to a change, however small, of a pattern of lines of force. Such images are sometimes very attractive.

The pattern of lines of forceThe pattern of lines of force

The field lines of the electric field is a way to help your mind to see the reality

Michael Faraday

Michael Faraday

The concept of an electric field arose when scientists tried to explain the long-range interaction that occurs between the charged objects. The idea of ​​an electric field was first introduced by physicist of the 19th century by Michael Faraday. It was the result of the perception of Michael Faraday invisible reality in the form of paintings describing long-range power lines. Faraday did not think in a single charge, but went ahead and expanded the boundaries of the mind. He suggested that the charged object (or mass in the case of gravity) affect the space and introduced the concept of the field of influence. Considering these fields he was able to explain the behavior of charges and thereby revealed many of the secrets of electricity.

The electric field refers to a category of things that are seen not with the eyes and mind. Image of force interaction in the form of lines of different types, as well as a different color colorings - just a way to help the mind to see the invisible. Electrostatics studies fixed charges, but in practice, in real life, the charges are in constant motion, which is much more difficult to represent the picture of the field. It turns out that it is necessary to see the dynamics of all what is depicted and defined by the electric field, but in this case more suitable not individual images, and their animation sequence.

Date: 01.28.2016

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© Valentin Grigoryev


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