Later, people's understanding of electricity developed, but the name charge remained.
Charge is the amount of electricity carried by a substance, atom or electron. The unit is Coulomb (labeled C), abbreviated as Library.
We often refer to "charged particles" as charges, but charges themselves are not "particles", just for the convenience of description, we often think of them as particles. So people with more charges have more charges, and the amount of charges determines the size of the force field (coulomb force). In addition, according to the directionality of electric field force, charges can be divided into positive and negative charges, and electrons are negatively charged.
According to Coulomb's law, objects with the same charge will repel each other, and objects with different charges will attract each other. The repulsive force or attractive force is proportional to the product of charge.
point charge
Point charge is an ideal model of charged particles. There is no real point charge. Only when the distance between charged particles is much larger than the size of particles, or the influence of the shape and size of charged particles on the interaction force is negligible, can this charged body be called "point charge". Inherent properties of matter. There are two kinds of charges: positive charge and negative charge. Due to friction, heating, radiation and chemical changes, an object is positively charged when it loses some electrons, and negatively charged when it gains some electrons. Objects with excessive positive or negative charges are called charged bodies, sometimes called charges.
There is an interaction between charges. Static charge produces electrostatic field in the surrounding space, while moving charge produces magnetic field and electric field. Therefore, both static charge and dynamic charge are subjected to electric field force, and only dynamic charge can be subjected to magnetic field force.
Whether the actual charged body can be regarded as a point charge is not only related to the charged body itself, but also depends on the nature and accuracy of the problem. Point charge is a necessary abstract concept when establishing basic laws, and it is also an indispensable analytical means when analyzing complex problems. For example, the establishment of Coulomb's law and Lorentz's law, the quantitative study of the interaction between electric field and charged body, the introduction of experimental charge and so on. The concept of point charge is applied.
Particle charge
In particle physics, many particles are charged. Charge is an additive quantum number in particle physics, and the law of charge conservation also applies to particles. The sum of the charges of particles before the reaction is equal to the sum of the charges of particles after the reaction, which is strictly true for strong interaction, weak interaction and electromagnetic interaction.
Charge characteristic
There are only two kinds of charges in nature, namely, positive charge and negative charge. The charge of a glass rod rubbed with silk is called positive charge, and that of a rubber rod rubbed with wool is called negative charge. The most basic properties of charges are: like charges repel each other and different charges attract each other. One of the inherent properties of matter. It is the earliest discovery that amber can attract light and small objects after rubbing. Then it is found that lightning strike, induction, heating, irradiation, etc. can make objects charged. Electricity is divided into positive and negative, the same symbols repel, different symbols attract, positive and negative combine and neutralize each other. Electricity can be turned, and the total amount remains the same.
The basic unit of matter is atom, which is composed of electrons and nuclei, and the nuclei are composed of protons and neutrons. Electrons are negatively charged and protons are positively charged, which is the basic unit of positive and negative charges, while neutrons are uncharged. The so-called uncharged object means that the number of electrons equals the number of protons, and the charged object is the destruction of this balance. In nature, there is no charge that exists alone without matter. In an isolated system, no matter what happens, the total number of electrons and protons remains the same, but the combination mode or position changes, so the charge must be conserved.
In order to illustrate the characteristics of charge, we might as well make some analogies with mass. There are positive and negative charges, so there is a difference between repulsion and gravity of electricity. There is only one kind of mass, which always attracts each other. It is this difference that makes electricity shielded, but gravity cannot be shielded. A Einstein described the relativistic effect of mass changing with motion; However, the electric quantities of electrons, protons and all charged bodies will not change due to movement, and the electric quantities are relativistic invariants. The charge is quantum, and any charge is an integer multiple of the electron charge e. The exact value of e (suggested value 1986) is: e =1.60217733×10-20e-19. The difference (absolute value) between proton and electron charges is less than 65438. Electrons are very stable, and their lifetime is estimated to exceed 10 1 100 million years, which is much longer than the current predicted age of the universe.
The so-called fractional charge [1] refers to the charge smaller than that of electrons. If it exists, it will shake the position of electrons and protons as charge elements, which has important theoretical significance. 1964, M. Gail-Mann put forward the theory that hadrons are composed of quarks, and predicted that there are many kinds of quarks, and their charges are different. But there is no item about the existence of fractional charge, which belongs to the field of particle physics theory research. The symmetry of charge yoke parity (CP) involves the basic symmetry of space and matter, and has always been the frontier field of particle physics research. Cronin and Fitch won the Nobel Prize for discovering CP destruction. But what they found was only indirect CP destruction, which can be explained by weak action or ultra-weak action. In order to distinguish them, we must study direct CP destruction. This is not only of great significance for exploring new forces and theories in nature, but also plays a key role in understanding the origin of CP damage. Physicists began to study the direct damage of CP from 1964.
The direct destruction of CP in recent 40 years was explored, and a more accurate and self-consistent theoretical prediction was given, which was confirmed by two important experiments, NA48 of European Nuclear Center and KTeV of Fermilab in the United States. Therefore, experiments and theories establish the existence of direct CP failure in nature for the first time, successfully test the CP failure mechanism of the standard model, and exclude the ultra-weak interaction theory. At the same time, the project explains the so-called δ I = 1/2 rule that has puzzled the field of particle physics for nearly 50 years. It is recognized as "Beijing Group" by international peers and recognized and cited by major international experimental and theoretical experts. This project systematically studies some important physical phenomena in the Dualistic Hegelian Model (S2HDM) of spontaneous CP symmetry breaking, and points out that S2HDM can be a new physical model of the origin of CP breaking. Wu Yueliang has published dozens of papers in international core journals, with the total citation rate exceeding 1000 times. He is the main finisher of charge parity symmetry destruction and quark-lepton flavor physical theory research. Papers published in American Physical Review Letters (PRL) have been cited for more than 90 times.
Charge experiment
Charge produced by high voltage Two kinds of charges Student experiment: Divide students into groups.
The experimental equipment includes:
(1), two glass rods and two rubber rods;
(2) Two furs and two silks;
(3), bracket; In order to avoid the charge loss in the experiment, it is best for two students to operate at the same time;
Experimental process:
(1), two students rubbed the glass rod with silk at the same time to make it charged. Put one on the bracket. Note: Remember which end is charged. Don't touch the live end with your hand. Use the charged end of another glass rod to approach the charged end of this glass rod and observe what will happen.
(2) Rub the rubber rod with fur and repeat the experiment just now;
(3) What we did just now was a glass rod with silk and a rubber rod with wool.
Experimental summary; People have done a lot of experiments with various materials. It is found that charged objects attracted by glass rods rubbed with silk must repel each other with rubber rods rubbed with wool. All rubber rods and fur will attract each other, while glass rods and silk will repel each other. In other words, the charge of an object is either the same as that of a glass rod rubbed by silk or the same as that of a rubber rod rubbed by fur. There is no third possibility. There are only two kinds of charges in nature. Franklin, an American scientist, defined these two kinds of charges: the charge of a glass rod rubbed by silk is called positive charge, and the charge of a rubber rod rubbed by fur is called negative charge. 1, law of charge interaction: like charges repel, opposite charges attract, and the size is calculated by Coulomb's law. 2. Point charge force is a pair of interaction forces, following Newton's third law. 3. Applicable conditions of Coulomb's law: the interaction between static point charges in vacuum (even charged bodies and even charged spherical shells).
Charge history
The charge of asphalt is 65,438+0,785, and Coulomb (C.A. Coulomb, 65,438+0,736-65,438+0,806) obtained the law of electrostatic action through his torsion balance experiment, and mankind entered the quantitative study of electromagnetic phenomena.
1820, H.C. Oster (1771-1851) discovered the magnetic effect of current.
1820, A.M. Ampè re (1775-1836) discovered the law of interaction between currents.
183 1 year, Faraday (M. Faraday, 179 1- 1867) discovered the law of electromagnetic induction.
1864, Maxwell (J.C. Maxwell, 183 1- 1879) put forward the electromagnetic field equations on the basis of summarizing the experimental laws of predecessors, and predicted the existence of electromagnetic waves from his equations, and then pointed out the electromagnetic nature of light.
1887, Hertz (1857- 1894) proved the existence of electromagnetic waves through experiments, and simplified Maxwell's equations.
1895, Lorenz (H.A. Lorenz, 1853- 1928) published the Theory of Electrons, and gave the force formula of charge in electromagnetic field. At this point, the foundation of classical electromagnetic theory has been established.
1897, J.J.Thomson (1856- 1940) discovered the electron (e-) in the cathode ray tube, which is the first elementary particle found in human history. Physicists have discovered a large number of charged or electrically neutral particles, including protons (P), positrons (e+) and neutrons (N).
Discover the accusation
Nanoparticles Release Charge1897 J.J.Thomson discovered electrons in the cathode ray experiment, which is the first elementary particle discovered by human beings. In 2003, R.A. Millikan used the "oil drop" experiment to measure the charge-mass ratio of electrons for many times.
19 1 1E。 Rutherford put forward an atomic nucleation model based on the scattering experiment of particle colliding with metal foil. 1920 speculated that there should be a neutral particle in the nucleus besides the positively charged "proton".
1930a.m. Dirac introduced relativity into quantum mechanics, put forward relativistic electron theory, and predicted the existence of antiparticle positrons of electrons (and also predicted the existence of magnetic monopoles).
1932 C.D. Anderson discovered positrons in cosmic rays, which confirmed Dirac's prediction that J. chadwick discovered neutrons, and confirmed Rutherford's conjecture that W. K. Heisenberg and Ivanikov established the hypothesis that the nucleus was composed of protons and neutrons respectively.
1935 H. yukawa put forward the theory of strong interaction mesons; 1950, C. F. Powell discovered the p meson in cosmic rays.
1937 c.d. Anderson discovered the m particle in cosmic rays.
1947- Many strange particles were found in cosmic rays and accelerators: L hyperon, K meson, X hyperon, W hyperon 1955 O.Chamberlain and E. G. Segre found antiprotons in accelerators.
1964 M.Gell-Mann and G.Zweig put forward the quark model of hadron structure. Since the 1980' s, the theoretically predicted bound quarks and antiquarks have been discovered in the electron-proton collision experiment of the accelerator (the heaviest T quark was not discovered until 1995).
1964 a group of scientists found an anti-deuteron composed of anti-proton and anti-neutron in CERN accelerator.
1983 C.Rubbia et al. discovered W and Z0 particles predicted by the theory of electroweak unification in CERN.