Field strength (what is field strength)

1. The charged amount is Qfield strength, radius R, the internal and external field strength and potential distribution of a uniformly charged sphere, the internal field strength E=0, the external equivalent of the sphere is a point of charge at the center of the sphere E= KQr^2rR The potential is equalfield strength, the outside of the sphere is equivalent to a point charge Φ=KQr at the center of the sphere. If it is a uniformly charged sphere, the result is the same as the spherical shell. Outside the sphere, this spherical shell can be equivalent to a point charge with all charges concentrated in the center of the sphere. The potential distribution is k*4paiR^2σrfield strength; First of all, it should be clear that Gauss's theorem can be used to solve the field strength formula in a uniformly charged sphere, and this formula is indeed inversely proportional to the cubic power of the distance r. Specifically, the electric field strength E in a uniformly charged sphere and the radius of the sphere R and the distance r from the point to the center of the sphere is E=kQrsup2Rsup3 The core idea of Gauss's theorem is to solve the electric field generated by charges in a closed surface through the electric flux of the surface; The electric field strength of an infinitely long charged line is E=λ2πε 0r Gauss's theorem. Make a cylindrical surface with radius r and height h. The axis of the cylinder coincides with the charged line. The field strength on the cylinder is the field strength of the distance r from the line outside the line. E2πrh=λhε0, which results in E=λ2πε 0r, where λ is the line density of charge on the charged line. The knowledge expands the electric field refers to a special acting force produced by charges in space. This acting force is one of the basic phenomena of electromagnetic phenomena; According to the Lorentz force formula F=qE+v×B, the relationship between the field strength E and the velocity v can be deduced. Since the force of the magnetic field force on the charge is F=qv×B, the direction of the force is perpendicular to the plane of the velocity v and the magnetic induction intensity B. Therefore, the relationship between the field strength E and the velocity v is E=v×B4 The relationship between the field strength E and the quantity of charge q can be deduced. The relationship between electromotive force and electric field strength is as follows: The field strength has no direct relationship with the potential, because the value of the potential at a certain point is relative to the selected zero-point potential. The selected zero-point potential is different, and the field strength is unchanged. The zero potential can be artificially selected, and whether the field strength is zero is determined by the electric field itself. Introduction to potential energy 1 In electrostatics, potential energy is the potential energy of the charge distribution in the electric field, which is distributed with the charge in the system; The linear density of the rod is QL, then the field strength kQLdxr^2=kQdxLr^2 at a distance of d, integrating from d to d+L, and the direction E= kQL1d1d +L is directed towards the outside of the rod. 2 If the linear density of the rod is QL at a distance of d, then kQLdxr^2= kQLdxLr^2E = kQL1Ld1d at a distance of d, heading backwards.

2. The field strength is the electric field strength. It is a physical quantity that describes the nature of the electric field. The following is a specific explanation of the field strength. The electric field strength is defined as the ratio of the electric field force F exerted on a charge placed in a certain point in the electric field to its charge quantity q. The mathematical expression is expressed as E = Fq where E represents the electric field strength, F represents the electric field force exerted on the charge at that point, and q represents the charge quantity of the charge. The physical meaning of the electric field strength reflectsfield strengthDetermine the strength of the electric field at a certain point.

3. As shown in the following figure, the common calculation formulas for electric field strength mainly include the following: 1E =Fq. This is a definition of electric field strength and is applicable to the calculation of all electric field strength. E represents the field strength of a certain point in the electric field, F represents the electric field force exerted on the trial charge placed at this point. q refers to the charge amount of the trial charge. In this formula, E has nothing to do with F and q. There is no relationship between E and F proportional to q. 2E =kQr^; Let the charging amount of the charges at the two points be q, the distance is R, and the positive direction is to the right. 1 The characteristics of the field strength are on the line connecting two equal positive charges, from point A to point B, the magnitude of the electric field strength decreases first and then increases., that is, at the midpoint O, the minimum field strength is 0; The radius ratio of S1 and S2 = r1r2, so the area ratio S1S2 = r1^2r2^2E1E2 =1 is equal, and the reverse combined field strength is 0. How to calculate the field strength inside a sphere with q-charged? Gauss's theorem is made at a distance from the center of the sphere r, and the electric flux on the sphere is 43π r #179 ×δε. Because the field strength is uniformly distributed, the magnitude of the field strength can be directly divided by the area 4π r #178.

4. Electric field strength is a physical quantity used to express the strength and direction of the electric field. Experiments have shown that at a certain point in the electric field, the ratio of the electric field force received by the positive charge at the trial point to the charge carried by it is a quantity that has nothing to do with the charge at the trial point. Therefore, the direction of the electric field force received by the positive charge at the trial point is the electric field direction. The vector with the aforementioned ratio as the magnitude is defined as the electric field strength at the point. E is often used to represent the field strength and other objects; In general, the conversion and comparison between power dBm and field strength dBuvm requires combining multiple factors such as antenna gain test equipment and communication environment to achieve the best performance of wireless communications.

5. Transform the formula, U=Ed, U is the potential difference between two points or two equipotential surfaces in the electrostatic field, also called voltage E is the field strength. In this formula, it should mean that the field strength of the uniform electric field d is the distance between the equipotential surfaces where the two points are located. The physical meaning of the above formula is that the voltage between the two equipotential surfaces is equal to the product of the field strength and their distance, which is consistent with the meaning of the field strength and voltage. At a certain point in the electric field, try; The solution is first set to make A plate capacitor composed of two parallel plates that are close to each other. The areas of the plates are both S. Let the two plates have a charge of +Q respectively. The charge density of each plate is σ=QS. Remove the edge effect of the plates, so the electric field between the plates can be regarded as a uniform electric field. According to Gauss's theorem, the field strength between the two plates is E=σε. From the formula of plate capacitance, C=S4πkd; Field strength and electric field strength are the same physical concept. The following is a detailed explanation of their relationship. Definitions. The same field strength and electric field strength are both used to describe the strength and direction of the electric field. They are the basic physical quantity symbols of the electric field. They are both represented by the symbol E to distinguish them from other physical quantity measurement formulas. General electric field situation E=Fq, where E represents the electric field strength, F is the force experienced by a charge in the electric field, and q is the common value of the charge quantity.