By: Madyarova Matluba
Abstract: Law of conservation of electric charge. Under normal conditions, microscopic bodies are electrically neutral, because the positively and negatively charged particles that make up atoms are bound together by electric forces and form neutral systems. If the electrical neutrality of the body is violated, then such a body is called an electrified body. In order to electrify a body, an excess or deficiency of electrons or ions of the same sign must be formed in it.
Key words: electricity, element, negative, positive, atom, electric charge, proton, neutron, nucleus, hydrogen atom
Such phenomena are observed in human life that cannot be explained according to the laws of mechanics, molecular physics and thermodynamics. For example, we can observe that when an air- inflated bubble is rubbed against fur and brought close to crumpled paper or other light objects, they are drawn into the bubble. Such phenomena are called charging (electrification) of bodies. The charge of objects can be strong or weak. Therefore, a physical quantity that characterizes the amount of electricity is introduced – a physical quantity called charge.
Charge is denoted by q and its unit is Coulomb (C). There are two types of electric charge. Benjamin Franklin proposed to conventionally call them “positive” (+) and “negative” (-) charges. It is known from the molecular- kinetic theory that all bodies are composed of atoms. The word atom is derived from the Greek word meaning “indivisible”.
Simply put, the ancient Greeks believed that all bodies are composed of indivisible particles. On this basis, the term atom was created. But later it was known that atoms can also be separated into components. In 1911, Ernest Rutherford discovered the “planetary” model of atomic structure.
According to this model, an atom is an electroneutral particle consisting of a positively charged nucleus and negatively charged electrons moving around it. Electron charge is q=e=-1.6•10^(-19) C. Its mass is m_e=9.1•10^(-31) kg. Electron charge is the smallest elementary charge and can also be denoted by the letter e. Charges of the same sign repel, and charges of different signs attract. It is in this case that the atomic nucleus and its electrons attract each other and the electrons move around the nucleus. The kernel itself is divided into components. That is, it consists of positively charged protons and uncharged neutrons. Masses of proton and neutron are almost equal to each other and are 1836 times greater than the mass of electron: m_p=m_n=1836•m_e=1.66•10^(-27) kg. So the mass of one proton or one neutron is equal to 1 u.=1.66•20^(-27) kg. In addition, atomic mass is embodied in its nucleus. Because the mass of electrons is very small. Therefore, it is sufficient to calculate the nuclear mass when calculating the atomic mass. The number of electrons in an atom is equal to the number of protons in the nucleus. Therefore, the atom is electroneutral, that is, the total sum of charges is zero. Each element is represented by a chemical symbol. Here: X-element, A-mass number (total number of particles in the nucleus) or atomic mass; The number of protons in the Z-nucleus (nuclear charge), the order
number of the element in the periodic system. Then the equation A=N+Z is appropriate, N is the number of neutrons. Accordingly, the number 1 element of the periodic system, the nucleus of the hydrogen atom consists of one proton (no neutrons). The number two element helium (He) atom has two protons and two neutrons in its nucleus. Two electrons move around the nucleus. If an atom loses an electron as a result of an external influence, it becomes a positively charged atom, that is, a positive ion. If it receives an additional electron from the outside, it becomes a negative atom, that
is, a negative ion. For example, when a helium atom loses one electron, it becomes positively ionized He+. If it loses two, it is doubly ionized: He+2. If a hydrogen atom receives one extra electron, it becomes a negatively ionized H-. The study of electricity began with conducting simple experiments. Let’s try such an experiment. Let’s scatter pieces of paper cut with scissors on the table. Let’s take a plastic comb, clean it well and dry it. Then let’s comb our oil-free dry hair and bring it closer to the pieces of paper. Then we observe that the pieces of paper are stuck to the comb. A similar phenomenon can be observed by rubbing a ballpoint pen against a piece of wool, affecting scraps of paper, other light objects, and even a thin stream of water. Let’s cut the chocolate-wrapped celery metal paper 2 cm wide and wrap it around a pencil to make a cylinder. Then let’s make a hole in its end and hang it with a thread. If we bring a glass rod close to a cylinder suspended by rubbing