How to determine the direction of electric field lines and field strength

Discriminant method: The tangent direction of each point on the electric field line is the direction of the field strength at that point, that is to say, the tangent direction of each point of the electric field line is consistent with the field strength direction of the point. The instructions are as follows:

1. The concept of electric field lines.

In order to vividly describe the distribution of field strength, some directional curves are artificially drawn in the electric field, and the tangent direction of a point on the curve indicates the direction of the field strength at the point, and the density of the electric field line is directly proportional to the field strength at the point.

Electric field lines are also called power lines.

2. The relationship between the electric field line and the field strength.

The electric field line is marked with an arrow, indicating the positive direction that the tangent of each point on the line should take (i.e., the direction of the field strength of that point). Using electric field lines, the direction of the field strength at each point through which it passes can be determined, and thus the direction of the electric field force on a positive charge placed at that point can be expressed. The density of the electric field line is related to the small field strength, the electric field is strong at the dense part of the electric field line, and the electric field is weak at the sparse part of the electric field line.

In the same diagram, there are always some points where the field strength is equal to the small, then the density of the electric field lines at the location of these points should be the same, so we can add another one between the two electric field lines, but the electric field lines in other places should be treated the same to ensure that the electric field lines of the points with equal field strength are the same. After all the same methods are processed, the field strength of each point can be compared, and in fact, it is back to its original state.

If the electric field lines are marked with arrows, the electric potential decreases along the direction of the electric field lines. Because the arrow points to infinitesimal and the direction of the field strength is the tangent direction of the electric field lines. This is mainly a specific image to talk about

Connect the cable correctly, the connecting cable should not be too long. If long cables are not necessary, cable losses must be added to the meter readings, especially in the high frequency bands.

The field strength meter should measure not only the image carrier level, but also the FM sound broadcast signal carrier level, so the signal level used should include the sound carrier level and the image carrier level. The sound carrier level is defined as the effective value of the unmodulated sound carrier voltage at 75 terminals, expressed in dB V. The image carrier level is defined as the RMS value of the image carrier voltage at the modulation envelope peak (synchronization head) at the 75 terminal, expressed in dB V.

Therefore, the geophone for measuring the image carrier level should be a peak geophone, and attention should be paid when using it.

Use ambient temperature. In the middle of winter in the north, we should pay attention to taking thermal insulation measures, and in the south in midsummer, we should try to avoid putting the instrument directly under the sun, otherwise the reading error will greatly exceed the range of technical indicators.

When using the field strength instrument, it is necessary to move frequently, and be careful not to collide, so as not to damage the shell of the instrument and the accuracy of the pitch.

The field strength meter must be periodically measured or compared with the specially measured field strength meter to avoid inaccurate misjudgment of the instrument.

The left-handed can be judged.

In addition, instrumentation, compass, etc., can also be used to assist in judgment.

The direction of the electric field lines is along the electric field lines, while the direction of the field strength is the tangent direction of the electric field lines. There are differences.

Well, look at where the electric potential comes from

The direction of the electric field line can also be seen from the electrical point of view, generally + to -

Along the direction of the electric field lines, the electric potential decreases.

The field line depends on the specific topic.

The direction of the electric field is the same as that of the positive charge. The characteristic of the electric field is that there is a force acting on the charge, that is, the electric field force, so that the direction of the positive charge is the same as the direction of the electric field, and the direction of the negative charge is opposite to the direction of the electric field.

In order to vividly describe the distribution of field strength, some directional curves are artificially drawn in the electric field, and the tangent direction of a point on the curve indicates the direction of the field strength at that point. The denser the electric field lines, the greater the electric field strength.

Calculations

The electric field strength at a point in the electric field is numerically equal to the electric field force experienced by the unit charge at that point. The electric charge and volume of the test charge should be small enough to ignore its influence on the electric field distribution and accurately describe the electric field at each point.

The field strength is a vector quantity whose direction is positive and its magnitude is equal to the force experienced by the single anterior test charge. The unit of field strength is volt-meter, and 1 volt-meter = 1 bullhouse. The spatial distribution of field strength can be illustrated by the image of the electric field line.

The above content is referenced: Encyclopedia - Electric Field Strength.

Judgment skills of electric field strength direction: 1. The direction of the electric field force subjected to the positive charge at a certain point, that is, the direction of the electric field strength at that point. 2. The direction of the electric field strength is in the same straight line as the tangent of the electric field line and points to the direction of the electric potential reduction.

3. The direction of the electric field strength is perpendicular to the equipotential surface and points to the direction of the electric potential reduction.

The direction of the electric field force of the positive charge at a certain point is the same as that of the field strength at that point, along the tangent direction of the electric field line; The direction of the electric field force of the negative charge at a certain point is opposite to the direction of the field strength at that point; The opposite direction of the tangent direction along the electric field line.

The electric field force and the interaction between the charges take place through the electric field. As long as there is an electric charge, there is an electric field around the charge, and the basic property of the electric field is that it has a strong effect on the charge placed in it, and this force is called the electric field force.

The electric field force is the force exerted when an electric charge is placed in an electric field. or the force exerted in an electric field for a moving free charge. Its magnitude can be derived from Coulomb's law. When multiple charges act at the same time, their magnitude and direction follow the vector operation rules.

Application of electric field force: Due to the wide range of effects of electric field force, it is applied to ion accelerators, navigation correction in the aerospace industry, processing of new substances, changing the arrangement of particles inside materials, etc., and may be one of the main driving forces of engineering and technology in the future.

A method for judging the direction of electric field strength

1. Electric field line.

The tangent direction of a point along the direction of the electric field line is the direction of the electric field strength of that point. The tangent direction of any point on the electric field line, that is, the direction of the electric field strength at that point. So, if we know the electric field line distribution map, we can determine the direction of the electric field at any point.

2. The direction of the electric field force on the charge is judged.

According to the direction of the positive charge receiving electric field force and the direction of the electric field strength are the same, the direction of the negative charge receiving electric field is opposite to the direction of the electric field strength. Physically, it is stipulated that in an electric field, the direction of the electric field force experienced by a positive charge is the same as that of the electric field; The direction of the electric field force on which the negative charge is subjected is opposite to the direction of the electric field there. That is, the direction of the electric field force must be in the same straight line as the direction of the electric field, either in the same direction or in the opposite direction.

3. Equipotential surface.

The direction of electric field intensity is the direction in which the electric potential decreases the fastest in the electric field, and the equipotential surface is drawn, and the electric field lines are perpendicular to the equipotential surface. From the relationship between the electric field lines and the equipotential surface, it can be seen that the electric field lines are always perpendicular to the equipotential surface, and the electric potential decreases along the direction of the electric field. However, the direction of the electric potential decrease is not necessarily the direction of the electric field, but the direction of the electric field strength that should be measured by the surface field Hengda as the direction of the electric potential reduction speed (the largest potential difference per unit distance).

4. Field source charge method.

In the electric field around the positive field source charge, the direction of the electric field is diverging from the positive field source charge; In the electric field around the negative field source charge, the direction of the electric field is directed towards the negative field source charge.

The direction of the electric field line and the direction of the field strength are not necessarily the same, and the tangent direction of the electric field line is the same as the direction of the field strength. The direction of the electric field line and the direction of the field strength are not necessarily the same, and the relationship between the direction of the electric field line and the direction of the field strength is that the tangent direction of the electric field line is the same as the direction of the field strength. When the electric field line is a curve, the tangent direction of each point on the curve is the same as the direction of the electric field strength at that point, and when the electric field line is a straight line, the direction of the electric field line is the same as the direction of the field strength.