open lesson “Electricity in people’s lives” experiences and experiments on the world around us (preparatory group) on the topic

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Introduction

An analysis of industrial injuries shows that the number of injuries from electric current is insignificant and amounts to about 1%, however, of the total number of fatal accidents, the share of electrical injuries is already 20-40% and occupies one of the first places. first places. The greatest number of cases of electric shock, including fatalities, occurs during the operation of electrical installations with voltages up to 1000 V, which is due to their prevalence and relative accessibility to almost everyone who works in production. Cases of electric shock during the operation of electrical installations with voltages above 1000 V are rare, which is due to the insignificant distribution of such electrical installations and their maintenance by highly qualified personnel.

The main causes of electric shock at work are: accidental contact with non-insulated live parts of electrical equipment, the use of faulty hand-held power tools, the use of non-standard or faulty portable lamps with a voltage of 220 or 127 V., work without reliable protective and safety equipment; touching ungrounded electrical equipment housings that are energized due to insulation damage; non-compliance with the rules of design, technical operation and safety rules during the operation of electrical installations, etc.

Irritation of body tissues as a result of the action of electric current can be direct, when the current passes directly through these tissues, and reflexive (through the central nervous system), when the tissues are not in the path of the current.

Electricity. Both friend and foe

Humanity's dependence on electricity is increasing from year to year . Even minor shutdowns cause a lot of problems. In the event of large-scale outages, alternative energy sources will not be enough to fully supply cities and industrial facilities.

Energy creates one of the foundations of modern civilization and is increasingly polluting the environment . The Earth's climate is changing, which could lead to a global catastrophe. While scientists are looking for a way out of this situation, everyone can help in the safe and rational use of electricity.

Saving and careful use of any resources, including electricity, are necessary. Any consumer who turns on the lights in the house knows how much effort is spent on making life safer, more convenient and easier. A culture of energy consumption means using it wisely. First of all, this is compliance with safety regulations.

The modern world cannot exist without electricity . This is a fact that does not require confirmation. If it suddenly disappears, civilization will be destroyed. Therefore, humanity has no other way but the further development of the energy industry.

General characteristics of electrical energy

Electricity is widely used in industry, transport, agriculture and everyday life.

The wide and varied use of electrical energy is explained by its following features:

• electrical energy can be obtained from other types of energy: mechanical, thermal, nuclear, chemical, radiation;
• large amounts of electrical energy are transmitted over long distances at the speed of light with relatively little loss. Nowadays, there are power lines over a thousand kilometers long;
• electrical energy is easily distributed between sensors in almost any part. In communications, automation and measurement technology, devices are used whose power is measured in units or even tenths of watts. At the same time, there are electrical devices (motors, heating installations) with a capacity of thousands and tens of thousands of kilowatts;
• Electrical energy is relatively easily converted into other types of energy: mechanical, thermal, radiation, chemical. The conversion of electrical energy into mechanical energy with the help of electric motors allows the most convenient, technically perfect economy to drive a variety of machines and mechanisms in industry, agriculture, transport and everyday life. Electric light sources provide high-quality artificial lighting.

We can no longer imagine life without televisions, radios, tape recorders, refrigerators, vacuum cleaners, washing machines, electric irons, and electric kitchen appliances. All this is electrification, with the help of which man has increased his strength a million times. The comprehensive mechanization of human energy activity has led to an unprecedented complication of technical systems and their management.

There is an urgent need to increase human intellectual activity. Man made a qualitative transition in this area, inventing the electronic computer (computer) - the engine of a new scientific and technological revolution. Its main task is the automation of human intellectual activity, and in the future - the creation of artificial intelligence.

Man has put the power of electricity at his service. But in addition to the benefits that electricity provides, it is a source of great danger, and the intensity of its use increases the threat of this danger. It should be noted that when developing technology, a person creates it as less dangerous as possible, creates appropriate means of protection from danger, and chooses methods of action taking into account the danger. But, despite these measures, with the development of electrical engineering and the increase in its use, the danger is growing faster than human resistance. What are the dangers of electricity? To answer this question, you need to know the nature of electricity and its effect on the human body.

Electricity is a set of phenomena caused by the existence, movement and interaction of electrically charged bodies or particles.

Electric current is the ordered (directed) movement of electrically charged particles.

The current in metals is due to the presence of free electrons, in electrolytes - ions. Of course, the force causing this movement is the strength of the electric field within the conductor, which is determined by the electrical voltage at the ends of the conductor.

The presence of electric current in conductors leads to their heating, changes in chemical composition and the creation of a magnetic field.

Electrical devices, installations, and equipment that a person deals with pose a great danger to him, which is aggravated by the fact that human senses cannot detect the presence of electrical voltage, such as heat, light or mechanical energy, from a distance. Therefore, the body’s protective reaction manifests itself only when exposed to direct electric current. The second feature of the electrical effect on the human body is that the current passing through a person acts not only at points of contact and along the path of flow through the body, but also causes reflex disturbances in the normal functioning of a person. organs (cardiovascular system, respiratory system). The third feature is the possibility of receiving electrical injuries without direct contact with live parts - when moving on the ground near a damaged electrical installation (in the event of a ground fault), injuries from an electric arc.

Energy, its role in the modern world

Introduction.

When we talk about energy, we usually mean electricity. Therefore, from here onwards, when speaking about energy, I will mean electricity. And further I will develop only this direction.

We have always been and are proud of the discoveries of the “giants” in electricity generation. This always caused great delight among the majority of the population. This meant that there would always be light and warmth in the house so familiar to us; showed our power in front of other countries; We also wanted to prove what a person has achieved and what he can do... We can list a lot, but then, and maybe now, it was such an ideology, a principle of life. Rejoicing at the new discoveries of supergiants, we did not think about the consequences, about its role in the ecology of nature. For decades now, humanity has known many alternative energy sources that are cleaner, more economical and even more efficient. Why I don’t use them is a difficult question. And this question is partially answered by the epigraph. You can give a small example: there is a large hydroelectric power station. Let's say that it supplies energy to the floor of the area. Let's consider the environmental and economic situation around it. Let me start with the fact that a lot of effort and money was spent on building the dam. While the dam is being built, the river must be temporarily diverted somewhere, that is, a channel must be dug (again costs). It is necessary to evict people from the flood zone. It takes hundreds of kilometers of cable to supply electricity to half the region. As a result, we see that the area is becoming swampy, a large area of ​​forests, fields, houses is flooded, trees are being cut down where the wires from the hydroelectric power station will pass to the consumer, although he may be at the other end of the area...

Let's consider an alternative. There are so-called mini hydroelectric power stations. There is no need to build dams, divert rivers, etc. for them. They, of course, provide less energy, but they are also less expensive and their impact on the environment is much less. If several such mini hydroelectric power stations are installed in the region, then together they will cause less harm than one large hydroelectric power station, the costs will also be less, and perhaps even more energy. In addition, there is no need to install many kilometers of wires, in which some of the energy is lost.

Perhaps the example is not entirely successful because mini hydroelectric power plants cannot be called environmentally friendly either. But today I do not know a single source of energy that would not have an impact on nature and humans to one degree or another. In principle, they hardly exist.

With this example I will end my introduction. Next, I will try to expand on the impending problem and bring my train of thought to the end.

Energy, its role in the modern world.

Starting the story about energy, I want to cite almost a catchphrase about money, but it is also relevant about energy: “... there may not be enough of it, there may be enough of it, but there is never too much of it...”. The electric power industry developed very rapidly in the 20th century. Thermal power plants, hydroelectric power stations, and nuclear power plants grew “like mushrooms after rain.” Energy consumption is growing at a colossal rate, and it continues to grow to this day. I want to give an example that I observed with my own eyes. For the last two summers I worked as a programmer at one of the fairly large enterprises in my city. What I saw last summer and this are two big differences. The number of computers doubled, electrical appliances (kettles, electric stoves, refrigerators, etc.), fans or air conditioners, and various types of electrical equipment appeared in almost every department, replacing manual labor. Even without calculating the costs of electricity, it is not difficult to see that consumption has increased by almost two.

In 1930, the world produced about 300 billion kilowatt-hours of electricity. But in 2000, about 30 thousand billion kilowatt hours were produced. Under the conditions of the modern demographic explosion, the world's population doubles in 40-50 years. At the same time, in the energy sector this happens every 12-15 years. Thus, the amount of energy per capita increases. But not every soul receives it, even in small quantities. The lion's share falls on developed and highly developed countries. And the problem usually arises in these countries.

In the modern world it is difficult to imagine life without electricity. The economies of many countries suffer billions of losses even if there is a slight “starvation” of electricity. There is a recent example of this in the USA and Canada. All enterprises, hospitals, homes, etc. rely on electricity. People's lives began to depend on electricity, both directly and indirectly.

Electrical appliances are considered to be “green” and therefore less harmful to human health and the environment. Yes, this is true, but it, that is, energy, still needs to be produced. And this is not always environmentally acceptable.

About the numbers...

In the world, about 80-85% of energy is produced from burning fuels (petroleum products, gas, various biological resources). Although, according to the trend of recent years, its share is gradually decreasing. Among the sources of combustion products, coal is the leader - 52% (in China - 75%, in Russia - 18%). In Russia, the predominant source of energy is natural gas – 40%. The share of oil in Russia accounts for no more than 10% (in the USA - 35). The world receives about 5-6% of energy from hydro resources (in Russia 20.5%). Nuclear energy accounts for 17-18%. In Russia its share is about 12%, and in a number of countries it is predominant in the energy balance. For example, France – 74%, Belgium – 61%, Sweden – 45%.

The main pollutant is the leader, i.e. power plants that burn fuel. They supply the atmosphere with technogenic carbon (mainly in the form of CO2), about 50% sulfur dioxide, 35% nitrogen oxides and the same amount of dust. According to some data, thermal power plants pollute the environment with radioactive substances 2-4 times more than nuclear power plants of the same power. Emissions from thermal power plants contain a significant amount of metals and their compounds. When recalculated into lethal doses, annual emissions from thermal power plants with a capacity of 1 million kW contain over 100 million doses of aluminum and its compounds, 400 million doses of iron, and 1.5 million doses of magnesium. Fatalities practically do not happen, because they enter the body in small quantities, but they specifically undermine health. It can be considered that thermal energy has a negative impact on almost all elements of the environment, as well as on humans. These impacts are summarized in Table 1.

The impact of energy on the environment and its inhabitants largely depends on the type of energy carriers (fuel) used. The cleanest fuel is gas, followed by oil (fuel oil), coal, brown coal, shale, and peat.

One of the most important impacts of hydropower is associated with the alienation of significant areas of fertile (floodplain) land for reservoirs. In Russia, where no more than 20% of electrical energy is produced through the use of hydro resources, at least 6 million hectares were flooded during the construction of hydroelectric power stations. lands. In their place, natural ecosystems have been destroyed. The main impacts of hydroelectric power stations on the environment, various parts of ecosystems and humans are shown in Table No. 2. Significant areas of land near reservoirs experience flooding as a result of rising groundwater levels. These lands, as a rule, become wetlands. In flat conditions, flooded lands can account for 10% or more of the flooded lands. The migration routes of fish are being disrupted, feeding grounds, spawning grounds, etc. are being destroyed. The Volga has largely lost its importance as a spawning ground for Caspian sturgeon after the construction of a cascade of hydroelectric power stations on it. There is evidence that, as a result of siltation, lowland reservoirs lose their value as energy facilities 50-100 years after their construction. For example, it is estimated that the great Aswan Dam, built on the Nile in the 60s, will be half silted up by 2025. Despite the relative cheapness of energy obtained from hydro resources, their share in the energy balance is gradually decreasing. This is due both to the depletion of the cheapest resources and to the greater territorial capacity of lowland reservoirs. It is believed that in the future, global energy production from hydroelectric power plants will not exceed 5% of the total. Reservoirs have a significant impact on atmospheric processes. For example, in arid (arid) regions, evaporation from the surface of reservoirs exceeds evaporation from an equal land surface by tens of times. About 6 km3 evaporates annually from the Volga-Kama reservoir cascade alone. This is approximately 2-3 annual water consumption standards in Moscow. Increased evaporation is associated with a decrease in air temperature and an increase in foggy phenomena. The difference in the thermal balances of reservoirs and the adjacent land determines the formation of local winds such as breezes. These, as well as other phenomena, result in a change in ecosystems (not always positive) and a change in weather. In some cases, in the area of ​​reservoirs it is necessary to change the direction of agriculture. For example, in the southern regions of our country, some heat-loving crops (melons) do not have time to ripen, the incidence of plant diseases increases, and the quality of products deteriorates.

Until recently, nuclear energy was considered the most promising. This is due both to relatively large reserves of nuclear fuel and to its gentle impact on the environment. The advantages also include the possibility of constructing nuclear power plants without being tied to resource deposits, since their transportation does not require significant costs due to small volumes. It is enough to note that 0.5 kg of nuclear fuel can produce the same amount of energy as burning 1000 tons of coal.

Until the mid-80s, humanity saw nuclear energy as one of the ways out of the energy impasse. In just 20 years (from the mid-60s to the mid-80s), the global share of energy produced by nuclear power plants increased from almost zero to 15-17%, and in a number of countries it became prevalent. No other type of energy has had such growth rates. Until recently, the main environmental problems of nuclear power plants were associated with the disposal of spent fuel, as well as with the liquidation of nuclear power plants themselves after the end of their permissible operating lives. There is evidence that the cost of such liquidation work ranges from 1/6 to 1/3 of the cost of the nuclear power plants themselves. By May 1986 400 power units operating in the world and providing; more than 17% of electricity, increased the natural background radioactivity by no more than 0.02%. Before the Chernobyl disaster in our country, no industry had a lower level of occupational injuries than nuclear power plants. 30 years before the tragedy, 17 people died in accidents, and then for non-radiation reasons. After 1986, the main environmental danger of nuclear power plants began to be associated with the possibility of accidents. Although their likelihood at modern nuclear power plants is small, it cannot be ruled out. As a result of the accident at the Chernobyl nuclear power plant, an area within a radius of more than 2 thousand km, covering more than 20 countries, was exposed to radioactive contamination. Within the former USSR, 11 regions, home to 17 million people, were affected. The total area of ​​contaminated areas exceeds 8 million hectares, or 80,000 km2. According to various sources, the total release of fission products contained in the reactor ranged from 3.5% (63 kg) to 28% (50 tons). For comparison, we note that the bomb dropped on Hiroshima yielded only 740 g of radioactive material.

In general, the following impacts of nuclear power plants on the environment can be mentioned:

• destruction of ecosystems and their elements (soils, soils, aquifers, etc.) in places of ore mining (especially with the open method);
• seizure of land for the construction of nuclear power plants themselves. Particularly large areas are alienated for the construction of structures for supplying, draining and cooling heated water. A 1000 MW power plant requires a cooling pond with an area of ​​about 800-900 hectares. Ponds can be replaced by giant cooling towers with a diameter at the base of 100-120 m and a height equal to a 40-story building;
• withdrawal of significant volumes of water from various sources and discharge of heated water. If these waters enter rivers and other sources, they experience a loss of oxygen, the likelihood of flowering increases, and the phenomena of heat stress in aquatic organisms increase;
• Radioactive contamination of the atmosphere, water and soil cannot be ruled out during the extraction and transportation of raw materials, as well as during the operation of nuclear power plants, waste storage and processing, and their disposal.

Is there a way out?

Now I have come to the final and important part of the essay. Here I will try to talk about alternative types of energy production. I believe that the problem is not only in obtaining energy, but in its rational use. It is necessary to develop and implement technologies with low electricity consumption. But, as always, the problem is money, or rather the lack of it. Solving this problem will not solve the main problem - obtaining a “safe” source. I put the word safe in quotation marks because an absolutely pure source does not exist. Perhaps a perpetual motion machine, but it hasn’t been invented yet. It is also necessary to improve existing power plants. They are unlikely to be abandoned in the near future. Yes, until they create and implement a clean method of producing energy, it must be obtained from somewhere. And all this time it will affect the environment and people.

Let's consider some ways and methods of use that can significantly reduce the negative impact on the environment. These methods are based mainly on improving technologies for fuel preparation and hazardous waste collection. Among them are the following:

1. Use and improvement of cleaning devices. Currently, many thermal power plants mainly capture solid emissions using various types of filters. The most aggressive pollutant, sulfur dioxide, is not captured at many thermal power plants or is captured in limited quantities. At the same time, there are thermal power plants (USA, Japan) that perform almost complete removal of this pollutant, as well as nitrogen oxides and other harmful pollutants. For this purpose, special desulfurization (to capture sulfur dioxide and trioxide) and denitrification (to capture nitrogen oxides) installations are used. The most widespread capture of sulfur and nitrogen oxides is carried out by passing flue gases through an ammonia solution. The end products of this process are ammonium nitrate, used as a mineral fertilizer, or a solution of sodium sulfite (raw material for the chemical industry). Such installations capture up to 96% of sulfur oxides and more than 80% of nitrogen oxides. There are other methods of purification from these gases.

2. Reducing the entry of sulfur compounds into the atmosphere through preliminary desulfurization (desulfurization) of coal and other types of fuel (oil, gas, oil shale) by chemical or physical methods. These methods make it possible to extract from 50 to 70% of sulfur from fuel before it is burned.

Features of the effect of electric current on the human body

Electric current, passing through the human body, predetermines the transformation of electrical energy absorbed by the body into other types and causes thermal, electrolytic, mechanical and biological effects.

The most complex is the biological effect, which is unique to living organisms. Any conductor has thermal and electrolytic effects.

The thermal effect of electric current is characterized by heating of tissues up to the point of burns.

Statistics show that burns account for more than half of all electrical injuries. They are treatable because they penetrate deeply into the tissues of the body. In electrical installations with voltages up to 1 kV, contact burns are most often observed when the body comes into contact with live parts.

Burns are possible when a current of more than 1A passes through the human body. Only with a high current, tissues are affected, heated to a temperature of 60-700C and higher, at which the protein coagulates and burns appear.

In almost all cases, when a person is included in an electrical circuit on his body and in places of contact, “electrical signs” of gray-yellow color, round or oval, are observed.

In case of burns from the action of an electric arc, metallization of the skin with metal particles from the arc plasma is possible. The affected area of ​​the skin becomes hard and takes on the color of metal salts stuck in the skin.

The electrolytic effect of current is expressed in the decomposition of organic liquid, including blood, which is an electrolyte, and in the disruption of its physical and chemical composition.

The biological effect of current manifests itself through irritation and excitation of living tissues of the body, as well as disruption of internal biological processes.

The mechanical effect of current leads to rupture of body tissue as a result of electrodynamic action, as well as an instant explosive connection with tissue fluid and blood.

Electric current or arcing may cause electric shock. Electrical injuries are conventionally divided into general and local. Local injuries include burns, electrical signs, electroplating of the skin, mechanical injuries, and electrophthalmia (inflammation of the eyes resulting from exposure to ultraviolet rays from an electrical arc).

General electrical injuries are also called electric shock. This is the most dangerous type of electric shock. Electric shocks cause excitation of living tissues, convulsive muscle contractions, paralysis of the muscles of the musculoskeletal system, muscles of the chest (respiratory), muscles of the ventricles of the heart.

The effect of electric current on living tissue, in contrast to the action of other material factors (steam, chemicals, radiation, etc.), has a unique and versatile character. Passing through the human body, electric current has thermal, electrolytic and mechanical effects. These physical and chemical processes are inherent in both living and inanimate matter. At the same time, the electric current also performs a biological effect, which is a specific process characteristic only of living tissue:

• The thermal effect of current is manifested in burns of individual parts of the body, heating to a high temperature of blood vessels, nerves, heart, brain and other organs located in the path of the current, which causes serious functional disorders in them;
• the electrolytic effect of current manifests itself in the decomposition of organic liquids, including blood, which is accompanied by significant disturbances in their physicochemical composition;
• The mechanical (dynamic) effect of the current manifests itself in rupture, delamination and other damage to various tissues of the body, including muscle tissue, walls of blood vessels, vessels of pulmonary tissue, etc.;
• The biological effect of current is manifested in irritation and excitation of living tissues of the body, as well as in disruption of internal bioelectric processes that occur during the normal functioning of the body.

An electric current passing through the body irritates living tissues, causing a response in them - excitation, which is one of the main physiological processes and is characterized by the fact that living formations move from a state of relative physiological rest to a state of specific activity. them.

It is necessary to consider the types of electrical injuries and causes of death from electric shock.

An electrical injury is an injury caused by an electric shock or arc. Depending on the consequences of electrical injuries, they are conventionally divided into two types: local electrical injuries, when local damage to the body occurs, and general electrical injuries (electric shock), when the entire body is affected as a result of a malfunction of the system. normal activity of vital organs and systems.

Typical local electrical injuries are electrical burns, electrical signs, skin metallization, mechanical injuries, and electrophthalmos.

Electrical marks (electrical marks) are gray or pale yellow callus-like spots on the surface of the skin where they come into contact with conductive parts.

Skin metallization is the penetration of tiny metal particles into the upper layers of the skin, which melts as a result of the action of an electric arc. This damage usually occurs on exposed parts of the body - the arms and face. The damaged area of ​​the skin becomes hard and rough, but in a relatively short time it regains its previous appearance and elasticity.

Electrophthalmia is eye damage caused by exposure to ultraviolet radiation from an electrical arc.

The most dangerous type of electric shock is electric shock, which in most cases (about 80%, including mixed injuries) leads to the death of the victim.

Electric shock is the stimulation of living tissues of the body by electric current, accompanied by convulsive muscle contraction. Depending on the consequences of the injury, electric shock can be divided into four degrees:

• convulsive muscle contractions without loss of consciousness;
• convulsive muscle contraction with loss of consciousness, but with preservation of breathing and heart function;
• loss of consciousness and disturbances in cardiac activity or breathing (or both);
• clinical death.

Clinical death is a transition period from life to death, which begins from the moment the heart and lungs stop and lasts 6-8 minutes until the death of brain cells. After this, biological death occurs, as a result of which biological processes in the cells and tissues of the body cease and protein structures collapse.

The degree of exposure to current when passing through the human body

There are three degrees of exposure to current when passing through the human body (alternating current):

• palpable current - the occurrence of painful sensations (up to 0-1.5 mA);
• current without release - convulsions and pain, heavy breathing (10-15 mA);
• fibrillation current - cardiac fibrillation with a current duration of 2-3 s, respiratory paralysis (90-100 mA).

Alternating current is more dangerous than direct current. With a current of 20-25 mA, the fingers convulsively squeeze the object taken in the hand, which is under tension, the muscles of the forearm are paralyzed, and the person cannot free himself from the action of the current. Many have paralyzed vocal cords: they cannot call for help.

What matters is the current through the body and especially the places where the current enters and exits. Of the possible paths of current passing through the human body, the most dangerous is the one in which the brain (head-arms, head-legs), heart and lungs (arms-legs) are affected. But there are cases of fatal electric shock when the current did not pass through the heart or lungs at all, but went, for example, through a finger or through two points on the shin. This is due to the presence of particularly vulnerable points on the human body, which are used in acupuncture treatment.

In the event of an electric shock, first of all, it is necessary to provide first aid to the victim.