Questions about the uniqueness of the electric field strength

e=f q is equivalent to a means or method of measurement.

For example, use a ruler to measure a person's height.

The size or attribute of a ruler is like F and Q, and the height of a person is like E.

A person's height does not change with the size or attributes of the ruler.

Although different people have different heights, this has nothing to do with the ruler itself.

Uniqueness: The electric field strength e at a point in the electric field is unique, and its magnitude and direction are independent of the charge q placed at that point.

It refers to the strength of the electric field, which is a property of the electric field itself, which is related to the position of the charge, but has nothing to do with the charge itself. Even if there is no charge at that location, the electric field strength is present and of a certain magnitude.

This applies to the fact that the electric field itself does not change, and the electric field itself does not need to be discussed.

What you said about e is inversely proportional to q, which is equivalent to changing another electric field to the ** problem.

So this uniqueness doesn't apply.

Instead of q being inversely proportional to e, it should be f=qe, and the electric field force is proportional to the charge or electric field strength.

In the same example, the resistance r is a property specific to a conductor. U=IR, although it can also be mathematically deformed as R=U i, it cannot be said that R is proportional to U. Because you can't increase the resistance of a conductor by increasing u.

In the same way, you can't increase q by lowering e.

Formula: e=f q, the larger q is, the larger f is, and the ratio of q to f does not change, that is, e does not change, so uniqueness is irrelevant.

Kiss.. Electric field strength is the property that the electric field itself possesses. Just like mass, density, it is a property, and of course it has nothing to do with the tentative charge.

That is to say, at a certain point in the electric field, the charge with a large amount of charge will be subjected to the corresponding electric field force. These two ratios are always constant.

Because when q changes, f also changes, and f q does not change, that is, e does not change.

An electric field is a physics that exists in space caused by an electric charge that exerts a force on other charges and can also affect the chain motion of the charge. Electric field strength is an important parameter of the electric field, which describes the magnitude and direction of the electric force experienced by a unit charge in the electric field, and is a basic tool for studying the properties of the electric field and the motion of the electric charge. The electric field strength is defined as placing a test charge at a point and measuring the ratio of the amount of electricity received to the test charge.

In the national shantung denier intermittent unit system, the unit of electric field strength is the cow coulomb (n c).

The electric field strength has a vector nature, i.e., it has a delay in magnitude and direction in space. In an electrostatic field, the electric field strength is closely related to the distribution of the electric charge and can be calculated by Coulomb's law. Coulomb's law states that the force between two charges is inversely proportional to the square of the distance between them and directly proportional to the product of their electric charge.

Therefore, in an electrostatic field, the magnitude of the electric field strength is related to the distribution of the charge at that point, the distance, and the nature of the medium.

The electric field strength plays an important role in the movement of the charge. In an electric field, the charge is subjected to the force of the electric field and accelerates or decelerates, thus changing the state of motion. When a charge moves in an electric field, the direction of the electric field strength and the direction of motion of the charge are not necessarily the same, and the product of the electric field force and the velocity of the charge determines the magnitude and direction of the resultant force on the charge.

Therefore, electric field strength is not only a basic tool for studying the motion of electric charges, but also a necessary condition for understanding important concepts such as electrostatic fields, electric field mediums, etc.

In conclusion, electric field strength is an important physical quantity in an electric field that describes the interaction between electric charges in an electric field. The definition and calculation of electric field strength is very important, and it plays a vital role in the study of electric field properties and the process of charge motion.

I also thought it was strange, and I looked it up on the Internet, and it seemed to be in a certain lesson plan. The original text found is as follows:

Uniqueness and fixity.

The electric field strength e at a certain point in the electric field is unique, and its magnitude and direction are independent of the charge q placed at that point, it is determined by the source charge and spatial position of the electric field, and the electric field strength corresponding to each point in the electric field has nothing to do with whether the charge is put in or not.

I think there's something wrong with this expression. It presumably wants to say that in the formula "e=f q", e is the objectively existing field, independent of the magnitude of q of the electric field force under investigation. However, when a charge q is placed in the field, the distribution of the field will inevitably change compared to before it is placed.

I don't know where you saw this sentence, but I personally think there is something wrong with the level of this expressor.

The strength of the electric field is the property of the electric field itself, just as mass is the property of an object itself, and its magnitude and direction do not change with the tentative charge.

There is a problem with the question itself, whether P is positive or negative.

If only under the action of the electric field force:

1. P is positively charged: then from A to B is the direction of the paraelectric field line. Because the electric field is a negatively charged electric field, the electric field lines are directed towards the field source charge and the field strength increases in the direction of the electric field lines. So the acceleration at point b is large. Spring stool.

2. P is negatively charged: then from A to B is the direction of the reverse electric field line. Because the electric field is a negatively charged electric field, the electric field lines are directed towards the field source charge and the field strength is enhanced in the direction of the electric field lines. The acceleration at point A is large.

This topic examines two corollaries derived from Coulomb's law: the electrostatic force formula and the point charge field strength formula, and the superposition principle of the electrostatic lead wheel field.

The field strength at a is superimposed by two parts: 1, the uniform electric field strength: by the electric field force formula f=qe, you can get e=f qa, bring it in and calculate it yourself (note that the power is negative, and the calculated field strength is also negative, that is, it is opposite to the direction of the force Hu Qi Lu trouser belt, so the direction of the field strength is horizontal to the left).

2.The field strength produced by charge b at a: the formula for the field strength of a little charge.

e=kqb r 2 brings in data that can be evaluated, (r=, the direction is vertically upward.

Finally, according to the superposition principle, the above two electric fields are vector summed, and their values can be calculated (using the parallelogram rule) (because they happen to be perpendicular, the Pythagorean theorem can be used).

The field strength at a is formed by the superposition of two parts: 1, the uniform electric field strength: by the electric field force formula f=qe, you can get e=f qa, bring it in and calculate it yourself (note that the power is negative, and the calculated field strength is also negative, that is, it is opposite to the direction of the force, so the field carries the strong direction to the left).

2.The field strength produced by charge b at a: the formula for the field strength of a little charge.

e=kqb r 2 brings in data that can be evaluated, (r=, the direction is vertically upward.

Finally, according to the principle of superposition, the above two electric fields are vector summed, and their values can be calculated (using the parallelogram rule).

Correct answer. a

The electric field is a vector, and the stacked front follows the four-sided Lingji letter rule of the flat ruler wheel line, and eo=0 and b are wrong and a is right from e=kq r 2 and the geometric relation.

on the x-axis. Bounded by point O.

Forward (negative) along x

The electric field intensity increases first and then decreases.

At point o, a point charge q, regardless of gravity, is released without initial velocity, and the charge f=0 will be stationary. CD error.

1) A and B are attracted to each other, analyze B, are subjected to the electrostatic force (attraction) of A, and remain stationary, must also be balanced by a force of equal magnitude in the opposite direction (electric field force) and the force of A, B has a negative charge, and the direction of the electric field force is opposite to the direction of the electric field, that is, the horizontal electric field direction is horizontal to the left, there is e kq r 9 10 9 2 10 -8n (3 10 -2) C 6 10 3n C

2) The field strength at the midpoint here is the vector sum of the electric field strength generated in A and the electric field strength generated in B, and the positive direction is specified from A to B, then the field strength of A at the midpoint C is E1 9 10 9 2 10 -8N (, the field strength of B is E1, so the vector sum is E3 3 10 3N CThe effect of the external electric field cannot be ignored, and the magnitude e4 -6 10 3n c (direction to the left) is superimposed, so the total field strength e'3 10 3n c, direction to the left.

In question 6, the field strength is inversely proportional to the square of the distance, and the distance ratio of point A and point C to q is 6 10 3 5

So the distance ratio at A and B is 3 4, so the field strength ratio is 16 9, so the field strength at point B is.

The difference between question 6 and (2) is that point b of question 6 is not affected by a and c, because here a and c are just points, not point charges, and point b is also just points and not charges. (2) In addition to the action of the external electric field, the midpoints of a and b are also affected by the field strength of a and b.

I did the right thing, I hope satisfied.

1 Gauss's theorem, the field strength of a point within a uniform sphere is equal to the field strength produced by a sphere within that point. e=k*q*(r^3/r^3)/r^2=kqr/r^3

2 Original formula = r 3[1-(l 2r) 2] (3 2)=r 3[1-3 2*(l 2r) 2)].

3 Original formula = r (-2)(1-l 2r) (2)=r (-2)(1+2l 2r)=r (-2)(1+l r).

4 Original formula = 1-1 2*LCOSA R=1-LCOSA 2R

5 Don't know what you're trying to ask.

When a tends to 0, sina=tana=a cosa=1-a2 2 (1 can also be taken when taking the 1st order approximation).

When x tends to 0, (1+x) n=1+nx (1-x) n=1-nx

ln(1+x)=x e^x=1+x

Your questions 2-4 are to put a factor in parentheses in the form of (1-x).

It's important to note that the approximate order is consistent, not higher. For example, tana=sina cosa, if you use the formula given above, you may think that under the 3rd order approximation, tana=a (1-a 2 2)=a+a 3 2, but this is wrong, because if you want to take the 3rd order approximation, you must consider the 3rd order term of sina, sina = a-a 3 6, and substituting it can get tana=a+a 3 3(In the same way, the fifth-order term here cannot be taken, and it is wrong to take it).

2 The formula for electric dipole moment takes the lowest-order approximation of the denominator under the far-field approximation. Because r1=nl 2+r (n is the direction vector) =r+l 2cosa is also an approximation on the numerator, the original expression should be r1 2=r 2+(l 2) 2+2cosar(l 2), if you carefully analyze the order of the denominator, the denominator cannot be taken at a higher order, for the same reason as I said last time. (If the denominator takes the second-order term of l (because there is no first-order term), the numerator must also take the second-order term).

3 If you don't write it wrong, or the book makes a mistake, the middle should be a minus sign (this formula should calculate the potential of the electric dipole moment, and the potential generated by the positive and negative charges is the reverse sign), so it is directly substituted. [(r-l 2)] 2)=r (-2)(1+l r)=1 r 2+l r 3 and [(r+l 2)] 2)=1 r 2-l r 3.