Tasks: Educational: find out how the induction current is directed in the circuit; to formulate the Lenz rule - Lesson

Electromagnetic induction. Rule Lenz.

Purpose of the lesson: to create conditions for understanding and understanding the essence Lenz rules.


Figure out how directed induction current in the circuit;

articulate Lentz rule;

to demonstrate on experiments and explain the phenomenon of self-induction;

check mastering the material studied


development logical thinking to explain results of experiments;

development intellectual skills of students (observe, apply previously learned knowledge in a new situation, analyze, draw conclusions);


form cognitive interest in the study of physical phenomena, cultivate public culture job skills.)

Type of lesson : presentation of the new of the material

During the classes

Organizational moment.

Today we with you in class we will get acquainted with EMP. what stands for electromagnetic induction.

Lesson begins with checking the studied material

Check test : (Annex 1)

Motivational stage

maybe whether the presence of current in a conductor without source current?

An experience : introduction of the strip magnet from a closed loop connected to galvanometer

Problem: Where does the current come from in a closed loop?

In case of difficulty students can be given several prompting questions:

what of yourself represents the contour? (Answer: contour closed)

what exists around a bar magnet? (answer: around the magnet there is a magnetic field)?

what appears when is a magnet introduced into the circuit? (Answer: closed loop permeates magnetic flux)

what's happening with magnetic flux when making (making) the magnet in a closed loop? (Answer: magnetic flux changes)

Conclusion:Cause of electrical closed loop current - change in magnetic flux, penetrating a closed loop.

This phenomenon was first discovered by Michael Faraday in 1820. It was called a phenomenon electromagnetic induction. (Message students about faraday ..)

Teacher: Electromagnetic induction - physical phenomenon consisting in the occurrence of a vortex electric field causing electric current in closed loop when changing flow magnetic induction through the surface bounded by this contour. Current, arising in a closed loop calledinduction .

Ways receiving induction current:

1.moving magnet and coil are relatively friend friend;
2. move one coil relative to another;
3. change in strength current in one of the coils;
4. closure and open circuit;
5. moving core;

An experience : key closure (opening)

Cause occurrence of current : the change in current in one circuit leads to a change in magnetic induction.

An experience moving the rheostat engine.

Cause occurrence of current : change in resistance in the first circuit leads to a change in current strength, and respectively, and change the magnetic induction

Teacher: From what size and direction depend induction current?

An experience : introducing the magnet first North Pole, then South Pole.

Conclusion : current direction depends on direction magnetic field and direction of movement the magnet.

An experience : insertion (removal) of the magnet in a closed circuit circuit first with one magnet then with two magnets

Conclusion : the amount of current depends on the value magnetic induction

An experience : We put the magnet at first slowly, then fast.

Conclusion : the amount of current depends on the speed making a magnet.

Interaction induction current with a magnet. If magnet close to the coil, then in it induction current appears such directions that a magnet is necessary repels. To bring the magnet closer and the coils need to make a positive work Coil becomes like the magnet facing the same pole to the magnet approaching it. The poles of the same name repel each other.

When deleting the magnet, on the contrary, arises in a coil current in such a direction as to appear attracting magnet force.

In what the difference consists of two experiments: approximation the magnet to the coil and its removal? AT the first case is the number of magnetic lines induction, penetrating the coil turns, or, equivalently, magnetic flux, increases (Fig. 2.5, a), and in the second case decreases (Fig. 2.5, b). And in first case of induction line magnetic field created by arising in a coil induction current coming out of the top the end of the coil, as the coil repels magnet, and in the second case, on the contrary, enter this end. These lines are magnetic inductions in figure 2.5 are black color. In the case of a coil with current similar to magnet, north pole which is on top, and in the case b - from the bottom.

This rule is can be confirmed by experience. In the installation, shown in the picture

At the ends rod that can rotate freely around the vertical axis, fixed two conductivealuminum rings . One of them with a cut. If you bring magnet to the ring without a cut, then in it induction current will occur and directed he will so that this ring will push off from the magnet and the rod will turn. If remove the magnet from the ring, then it is, on the contrary, will be attracted to the magnet. With cut ring magnet does not interact, so as a cut prevents the occurrence in the induction current ring. Repels or the coil magnet draws it depends on the direction of induction current in it. Therefore, the law of conservation energy allows us to formulate directional rule induction current.

The rule of Lenz. Now we come to the main point: increasing the magnetic flux through coil turns the induction current has such a direction that he creates magnetic field prevents amplification magnetic flux through the coil turns. After all, induction lines of this fields are directed against induction lines fields, a change which generates electrical current. If the magnetic flux through the coil weakens then the induction
current creates a magnetic field with induction , increasing magnetic flux through coil turns.

This is essence of the general rule of definition induction directions Teacher: To determine the direction closed loop induction current is usedthe rule Lenz :

Induction current has such a direction that created im the magnetic flux through the surface limited contour prevents change in the magnetic flux that caused this current.

Direction induction current depends on:
1) from ascending or descending magnetic flow permeating the contour;
2) from directions of magnetic induction vector contour fields

Direction induction current-

Rectilinear conductor:

Direction induction current is determined by right hand rule:

If put the right hand so that the vector magnetic induction was part of the palm set aside 90 degrees big finger pointing vector direction speed then straightened 4 fingers will show the direction of the induction current in the conductor.

Closed circuit:

Direction closed loop induction current determined by the rule of Lenz.

which eye applicable in all cases.

Rule Lenz-

Arising closed loop induction current its magnetic field counteracts change in magnetic flux which he is called.

Application Lenz rules
1. show the direction of the vector in the outer magnetic field;
2. define increases or decreases magnetic flow through the contour;
3. show vector direction of the magnetic field induction current (with decreasing magnetic flux vector In external field and Bi magnetic field induction the current should be directed equally while increasing the magnetic flux B and Bi should be directed oppositely);
4. according to the rule of gimlet to determine induction current direction in contour.

6. Homemade the task. (on cards) in a steel core transformer connected to voltage 220V (RNSH) make a closed contour with a light bulb. Why light up light bulb with it?

Teacher: Phenomenon electromagnetic induction found wide application in technology: transformers, magnetic trains, metal detectors (metal detectors), recording and information on magnetic media and reading from them

The result of the lesson. 1) What is the EMR phenomenon?

2) Recall experiences allowing to observe this phenomenon.

3) Who discovered the phenomenon AMY?

4) What we defined using the Lenz rule?

5) Application of EMR.

Check test : (Annex 1)

How to interact two parallel conductors if electric current flows into them one direction:

A) interaction force is zero;

B) conductors are attracted;

AT) conductors repel each other;

D) conductors turn in one direction.

In which case around a moving electron arises a magnetic field?

1) the electron moves uniformly and rectilinearly;

2) the electron moves evenly;

3) the electron moves equally accelerated.

D) there is no such case.

3. What is physical value has unit 1 Tesla?

A) magnetic flux;

B) magnetic induction;

AT) inductance.

4. flux magnetic induction through surface area S is determined by the formula:

B) Bstga ;

D) BScosa .

5. Closed Loop an area of ​​S turned 60? in uniform a magnetic field by induction B. With this magnetic flux permeating this circuit:

A) increased by 2 times;

B) decreased by 2 times;

AT) did not change.

6. In a closed loop area S, located in a uniform magnetic field increased amperage in 3 times. Magnetic flux penetrating this circuit, with:

A) decreased by 3 times;

B) increased by 3 times;

AT) did not change.

7 In a uniform magnetic field by induction 1 T are perpendicular to it two closed contours of 10 and 20 cm 2 respectively. Magnetic flux piercing the first circuit, compared with magnetic flux penetrating second circuit: charge should be placed in the center ...induction current depends on resistancecontour .Direction induction current determined by ruleLenz .Induction current alwaysdirected So...

  • Control of students' knowledge in physics


    Metal ring,as shown in the picture. Identifydirection induction current in the ring. 2. a) Through ... induction. Write down the formula. 12.Formulate the rule Lenz . 13.Explainthe rule Lenz based on conservation law ...

  • Educational and methodical complex of the discipline "introduction to physics" Code and direction of training

    Training and metodology complex
  • The subject of philosophy of science 4 Section I scientific knowledge as a sociocultural phenomenon 10


    ...as already shown, should summarize the experience of word usage and tryarticulate commonthe rule ...A task was toto figure out what are the magnitude anddirection ... economic,educational and...circuit ... chaininduction coils ...

  • 1) According to 1 figure. Indicate in which case the phenomenon of electromagnetic induction is observed:

    A. With a minimum value of resistance of the rheostat.
    B. With increasing resistance of the rheostat.
    B. At the maximum resistance value of the rheostat.
    G. With a constant value of resistance of the rheostat.

    2) What is the energy of the magnetic field of the coil with an inductance of 0.2 G at a current of 3 A?
    A. 0.3 J.
    B. 0.6 j.
    V. 0.8 j.
    G. 0.9 j.
    D. 1.5 J.

    3) Find the end of the statement that most fully reflects the essence of the phenomenon of electromagnetic induction: "In a closed loop, an electric current appears if ..."
    A. ... the circuit is in a constant magnetic field.
    B. ... the contour moves in a constant magnetic field.
    V. ... contour rotates in a constant magnetic field.
    G. ... the contour moves in a constant magnetic field so that the magnitude of the magnetic flux through the contour changes.

    4) Find the change in 3 ms of the magnetic flux through a circuit containing 80 turns of a wire with a resistance of 120 Ohms, if the induction current is 4 A:
    A. 1440 mVb.
    B. 18 mVb.
    V. 90 mVb
    G. 1.1 mVb

    5) By 2 figure. The graphs of the dependence of the magnetic flux penetrating the circuit on time are shown. Indicate the case when the induced emf increases:
    A. 1
    B. 2
    AT 3.
    G. 4.

    6) Where in fig. correctly shows the direction of the induction current arising in a closed loop as the magnet south pole approaches?
    A. 1.
    B. 2.
    AT 3.
    G. 4.

    1. The figure shows the direction of the magnetic field lines. In this magnetic field move the closed loop of the wire first

    vertically upwards so that the coil plane is parallel to the magnetic induction lines (situation A in the figure), then in the horizontal direction so that the coil plane is perpendicular to the magnetic induction lines (situation B in the figure). At what movement of the frame is a change in the magnetic flux?

    1) Only in A 3) Both in A and B

    2) Only in B 4) Neither A nor B

    2. The closed loop is located at a certain angle to the magnetic induction lines. How will the magnetic flux change if the modulus of the magnetic induction vector increases 3 times?

    1) Increase 3 times 3) Increase 6 times

    2) Decreases 3 times 4) Decreases 9 times

    3. The closed loop is located at a certain angle to the magnetic induction lines. How will the magnetic flux change if the area of ​​the circuit decreases by 2 times and the magnitude of the magnetic induction vector increases 4 times?

    1) Increase 2 times 3) Increase 4 times

    2) Decrease 2 times 4) Decrease 4 times

    4. Magnetic induction lines lie in the plane of a closed loop. How will the magnetic flux change if the modulus of the magnetic induction vector increases 3 times?

    1) Increase 3 times 3) Increase 9 times

    Right hand rule (mainly to determine the direction of magnetic lines
    inside the solenoid):

    If the solenoid is clasped with the palm of the right hand so that four fingers are directed along the current in the turns, then the left thumb will show the direction of the magnetic field lines inside the solenoid.

    Ticket 9. Electromagnetic induction.

    Electromagnetic induction

    The occurrence of an electric current in a closed conductive circuit, which either rests in a time-varying magnetic field or moves in a constant magnetic field so that the number of magnetic induction lines penetrating the circuit changes. The faster the number of magnetic induction lines changes, the greater the induction current.

    Methods for producing induction current



    (or flux magnetic induction)

    Magnetic flux through the surface with area S is called a value equal to the product of the modulus of the magnetic induction vector B and the area S and the cosine of the angle between the vectors B and n.

    The magnetic flux is proportional to the number of magnetic induction lines penetrating the surface with an area S.

    The magnetic flux characterizes the distribution of the magnetic field over a surface bounded by a contour.

    The magnetic flux in 1Vb is created by a uniform magnetic field with an induction of 1T through a surface of 1m2 located perpendicular to the magnetic induction vector.


    Straight conductor

    The direction of the induction current is determined by the rule of the right hand:

    If you put your right hand so that the vector of magnetic induction entered the palm, the thumb set aside 90 degrees indicated the direction of the velocity vector, then the straightened 4 fingers will show the direction of the induction current in the conductor.

    Closed loop

    The direction of the induction current in a closed loop is determined by the Lenz rule.

    Lenz Rule

    The induction current arising in a closed circuit with its magnetic field counteracts the change in the magnetic flux by which it is caused.

    Applying the rule of Lenz

    1. show the direction of the vector B of the external magnetic field;

    2. determine whether the magnetic flux through the circuit increases or decreases;

    3. show the direction of the vector Bi of the magnetic field of the induction current (when the magnetic flux of the vector B of the external magnetic field and Bi of the magnetic field of the induction current decreases, and when the magnetic flux increases, B and Bi should be opposite);

    4.according to the rule of gimlet to determine the direction of the induction current in the circuit.

    Ticket 10. Force Ampere. The rule of the left hand.


    This is the force with which a magnetic field acts on a conductor with a current.

    The Ampere force module is equal to the product of the current in the conductor and the magnitude of the magnetic induction vector, the length of the conductor and the sine of the angle between the magnetic induction vector and the direction of the current in the conductor.

    The Ampere force is maximal if the magnetic induction vector is perpendicular to the conductor.

    If the vector of magnetic induction is parallel to the conductor, then the magnetic field has no effect on the conductor with current, i.e. the Ampere force is zero.

    Ampere Force Direction determined byleft hand rule:

    If the left hand is positioned so that the component of the magnetic induction vector perpendicular to the conductor enters the palm, and the 4 extended fingers are directed in the direction of the current, the thumb bent by 90 degrees will show the direction of the force acting on the conductor with current.



    A homogeneous magnetic field orients the frame (i.e., a torque is created and the frame rotates to a position where the magnetic induction vector is perpendicular to the plane of the frame).

    A non-uniform magnetic field orients + attracts or repels a frame with a current.

    Ticket 11. Force Lorenz. Left hand rule

    Lorenz force

    The force acting from the magnetic field on a moving electrically charged particle.

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    The direction of the Lorentz force is determined byby left hand rule:

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    Since the Lorentz force is always perpendicular to the charge velocity, it does not perform work (that is, does not change the magnitude of the charge velocity and its kinetic energy).

    If a charged particle moves parallel to the magnetic field lines, then Fl = 0, and the charge in the magnetic field moves uniformly and straightforwardly.

    If a charged particle moves perpendicular to the magnetic field lines, then the Lorentz force is a centripetal

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    In this case, the particle moves in a circle.


    According to the second law of Newton: the Lorentz force is equal to the product of the particle mass by the centripetal acceleration

    then the radius of the circle

    and the period of circulation of charge in a magnetic field

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    Electric charges moving with a conductor in a magnetic field are affected
    Lorentz force:

    FL = / q / vB sin a

    q - charge (C)

    V - speed (m / s)

    B - magnetic induction (T)

    Its direction can be determined by the rule of the left hand.

    Under the action of the Lorentz force inside the conductor, the distribution of positive and negative charges occurs along the entire length of the conductor l.
    The Lorentz force is in this case a third-party force, and an induced emf appears in the conductor, and a potential difference arises at the ends of the conductor AB.

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    2. Indicate the direction of the induction current in the circuit when it is introduced into a uniform magnetic field.

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    4. Will there be induction current in conductors if they move as shown in the figure?

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    6. Indicate the correct direction of the induction current in the circuits.

    Thermal power engineering "href =" / text / category / teployenergetika / "rel =" bookmark "> thermal energy of the burned fuel is used in the steam generator, where a very high pressure of water vapor is set to drive the turbine rotor and, accordingly, the generator.As fuel, fuel oil or diesel is used at such thermal power plants, as well as natural gas, coal, peat, shale, in other words, all types of fuel. The efficiency of TPES is about 40%, and their capacity can reach 3-6 GW.


    Hydroelectric Power Plant (HPP) - power plant, as an energy source using the energy of the water flow. Hydroelectric power plants are usually built on rivers, building dams and reservoirs.

    For the efficient production of electricity at hydropower plants, two main factors are needed: guaranteed water supply all year round and possibly large river slopes, canyon-shaped landforms favor hydro-construction.

    Principle of operation

    The necessary water pressure is formed through the construction of the dam, and as a result of the concentration of the river in a certain place, or by derivation, by the natural flow of water. In some cases, to obtain the required water pressure, both the dam and the derivation are used together.

    Directly in the building of the hydroelectric power station is located all the power equipment. Depending on the destination, it has its own specific division.Hydroelectric units are located in the machine room, directly converting the energy of the flow of water into electrical energy. There are all sorts of additional equipment, control devices and control over the work of hydroelectric power plants, transformer station, switchgear and much more.

    Hydroelectric stations are divided according topower output :

    · Powerful - produce from 25 MW and above;

    · Medium - up to 25 MW;

    · Small hydropower plants - up to 5 MW.

    Hydropower capacity depends on the pressure and water flow, as well as on the efficiency of the turbines and generators used. Due to the fact that, according to natural laws, the water level is constantly changing, depending on the season, as well as for several other reasons, it is customary to take the cyclic power as an expression of the power of a hydroelectric station. For example, there are annual, monthly, weekly, or daily cycles of a hydroelectric power station.

    A small hydroelectric power plant typical of China’s mountain areas (Houzibao Hydroelectric Power Plant, Xinshan County, Yichang County, Hubei Province). Water comes from the mountain through the black pipeline

    Hydroelectric power plants are also divided according to the maximum use.water pressure :

    · High-pressure - more than 60 m;

    · Medium pressure - from 25 m;

    · Low pressure - from 3 to 25 m.

    3. TES

    Nuclear power plant (NPP) is a nuclear installation for the production of energy in specified modes and conditions of use, located within the territory defined by the project, in which a nuclear reactor (s) and a complex of necessary systems, devices, equipment and facilities with the necessary workers (personnel )

    The principle of operation of nuclear power plants is in many ways similar to the action of power plants on fossil fuels. The main difference is fuel. Uranium, a pre-enriched natural ore, is used in a nuclear power plant, and steam is produced by splitting the core, rather than burning oil, gas or coal. Nuclear power plants do not burn fuel, so that the atmosphere is not polluted. The process is as follows:

    The tiny particles of uranium, which are called atoms, are split.

    During splitting, even smaller atomic elements are released - neutrons.

    Neutrons collide with uranium atoms, as a result of which the heat required to generate electricity is released.

    Ticket 14. Types of ES. The influence of ES on the environment. Wednesday

    The environment is the basis of human life, and the fossil resources and energy generated from them are the basis of modern civilization. Without energy, humanity has no future. This is an obvious fact. However, modern energy causes significant damage to the environment, worsening the living conditions of people. The basis of modern energy - various types of power plants. At the dawn of the development of the domestic industry, 70 years ago, the main emphasis was placed on largeTPP . At that time, little was thought about the effect of thermal power plants on the environment, since the primary task was to obtain electricity and heat. Technology for the production of electrical energyTPP associated with a large amount of waste released into the environment. Today, the problem of the influence of energy on nature is becoming especially acute, since the pollution of the environment, the atmosphere and the hydrosphere is increasing every year. If we consider that the scale of energy consumption is constantly increasing, then, accordingly, the negative impact of energy on nature increases. If during the formation of energy in our country, first of all, they were guided by expediency in terms of economic costs,then today, with the construction and operation of energy facilities, the issues of their environmental impact are coming to the fore.

    Thermal power plants operate on relatively cheap organic fuel - coal and fuel oil, these are irreplaceable natural resources. Today, the main energy resources in the world are coal (40%), oil (27%) and gas (21%). According to some estimates, these reserves will last for 270, 50 and 70 years, respectively, and then subject to the current rates of consumption.

    Combustion of fuel at TPPs produces combustion products that contain: fly ash, particles of unburned pulverized fuel, sulfuric and sulfurous anhydride, nitrous oxide, and gaseous products of incomplete combustion. When fuel oil is ignited, vanadium compounds, coke, sodium salts, and soot particles are formed. In the ashes of some fuels, arsenic, free calcium dioxide, free silicon dioxide is present, which cause significant damage to all living things.

    Pollute the environment and waste water from thermal power plants containing petroleum products. The station discharges these waters after chemical flushing of equipment, heating surfaces of steam boilers and hydraulic ash removal systems.

    Sulfur oxide, which enters the atmosphere with great emissions, causes great damage to the animal and plant worlds, it destroys the chlorophyll found in plants, and leaves and needles are damaged. Carbon monoxide, entering the body of humans and animals, combines with the hemoglobin of the blood, as a result of which there is a lack of oxygen in the body, and, as a result, various disorders of the nervous system occur.

    Nitric oxide reduces the transparency of the atmosphere and contributes to the formation of smog. Vanadium pentaxide present in the ash composition is highly toxic, when released into the respiratory tract of humans and animals, it causes severe irritation, disrupts the activity of the nervous system, blood circulation and metabolism. A kind of carcinogen benzopyrene can cause cancer diseases.

    The largest branch of water use is hydro-power. With the construction of the plain hydroelectric station a negative point is the flooding of vast territories. To reduce the area of ​​land flooding, it is necessary to build protective dams. It is necessary to monitor the water level in the reservoirs in order to avoid temporary flooding of the coast; clean the bed of the future reservoir from shrubs, trees, and.etc .; on reservoirs to create conditions for the development of fisheries, since hydroelectric power plants are detrimental not only to agriculture, but also to fisheries.

    All hydroelectric power plants cause enormous damage to fisheries. Previously, events were proceeding in a constant evolutionary sequence: spring flood, the course of fish for spawning, the sliding of juveniles into the sea. And now, hydroelectric power stations are violating this order. The flood, called water release, occurs in the middle of winter, and by spring the ice layer settles on the flooded islands, crushing the wintering fish in the wintering pits, disrupting the biological ripening time of the roe. This means that it will be two years before the unripe caviar will resolve and a new one will be laid.

    The reservoirs increase the humidity of the air, contribute to a change in the wind regime in the coastal zone, while attacks on the temperature and ice drain regime. This leads to a change in natural conditions, which affects the economic activities of the population and the life of animals.

    The construction of hydropower plants should be designed with minimal environmental damage to nature.When developing, it is necessary to rationally choose a quarry, a location of roads, etc. Upon the completion of construction, work should be carried out to reclaim land disturbances and to green the territory. The most effective environmental protection measure is engineering protection. The construction of dams reduces the area of ​​flooding, saving it for agricultural use; reduces the area of ​​shallow waters; preserves the natural complexes; improves sanitary conditions of the reservoir. If the construction of the dam was not economically justified, the shallow waters can be used for breeding birds or other household needs.

    NPP. Usually, when they talk about radiation pollution, they mean gamma radiation, easily caught by Geiger counters and dosimeters based on them. At the same time, there are quite a few beta emitters that are poorly detected by existing mass devices. As well as radioactive iodine is concentrated in the thyroid gland, causing its defeat, radioactive isotopes of inert gases, which were considered absolutely harmless to all living things in the 70s,accumulate in some plant cell structures (chloroplasts, mitochondria and cell membranes). One of the main inert gases emitted is krypton-85. The amount of krypton-85 in the atmosphere (mainly due to the operation of nuclear power plants) is increasing by 5% per year. Another radioactive isotope that is not captured by any filters and in large quantities produced by any nuclear power plant is carbon-14. There is reason to believe that the accumulation of carbon-14 in the atmosphere (in the form of CO2) leads to a sharp slowdown in the growth of trees. Now in the composition of the atmosphere, the amount of carbon-14 is increased by 25% compared with the preatomic era.

    An important feature of the possible impact of nuclear power plants on the environment is the need to dismantle and dispose of items of equipment with radioactivity at the end of its service life or for other reasons. To date, such operations have been performed on only a few experimental setups.

    During normal operation, only a few nuclei of gaseous and volatile elements like krypton, xenon, and iodine enter the environment. Calculations show that even with an increase in nuclear power capacity by 40 times, its contribution to global radioactive contamination will not exceed 1% of the level of natural radiation on the planet.

    At power plants with boiling reactors (single-circuit), most of the radioactive volatile substances are released from the coolant in the turbine condensers, where, together with radiolysis gases, water is ejected into the special chambers, boxes or gas holders for primary treatment or incineration. The rest of the gaseous isotopes are released during the decontamination of the solutions in the holding tanks.

    In power plants with pressurized water cooled reactors, gaseous radioactive waste is released in holding tanks.

    Gaseous and aerosol waste from installation spaces, boxes of steam generators and pumps, protective covers for equipment, tanks with liquid waste are discharged using ventilation systems in compliance with standards for the release of radioactive substances. Air flows from the fans are cleaned from most of the aerosols on fabric, fiber, grain and ceramic filters. Before being discharged into the ventilation pipe, the air passes through gas settlers in which the decay of short-lived isotopes (nitrogen, argon, chlorine, etc.) takes place.

    In addition to emissions associated with radiation pollution, NPPs, as well as TPPs, are characterized by heat emissions affecting the environment. An example is the Vepko Sarri nuclear power plant. Its first unit was launched in December 1972, and the second in March 1973. At the same time, the water temperature at the surface of the river near the power plant in 1973. was at H4 вышеC above the temperature in 1971. and the maximum temperature was observed a month later. Heat is also released into the atmosphere, for which the so-called NPPs are used at NPPs cooling towers They emit 10-400 MJ / (mI · h) of energy into the atmosphere. The widespread use of high-power cooling towers raises new challenges. The cooling water consumption for a typical NPP unit with a capacity of 1,100 MW with evaporative cooling towers is 120 thousand tons / h (at an ambient water temperature of 14єC). With a normal salt content of the make-up water, about 13.5 thousand tons of salts that fall to the surface of the surrounding territory are released per year. To date, there are no reliable data on the environmental impact of these factors.

    The NPP provides for measures to completely eliminate the dumping of wastewater polluted with radioactive substances. In reservoirs it is allowed to divert a strictly defined amount of purified water with a concentration of radionuclides,not exceeding the level for drinking water. Indeed, systematic observations of the effects of nuclear power plants on the aquatic environment during normal operation do not detect significant changes in the natural radioactive background. Other waste is stored in containers in liquid form or previously converted to a solid state, which increases storage safety.

    Ticket 15.Items promysh. electronics - capacitors.

    A capacitor is a device for accumulating charge. It consists of two conductors - plates, separated by a dielectric.

    Designation on the diagram:

    The property of a capacitor - to accumulate and hold electric charges is characterized by its capacity. The greater the capacity of the capacitor, the greater the accumulated charge.

    The electrical capacity of a two-conductor system is called a physical quantity, defined as the charge ratio q one of the conductors to the potential difference Δφ between them:

    The simplest capacitor is a system of two flat conducting plates arranged parallel to each other at a small distance compared to the dimensions of the plates and separated by a dielectric layer. This capacitor is calledflat .

    Depending on the dielectric used, the capacitors are paper, mica, air. Using mica, paper, ceramics and other materials with high dielectric constant instead of air as a dielectric, it is possible to increase its capacitance several times with the same dimensions of a capacitor. In order to increase the area of ​​the capacitor electrodes, it is usually made multi-layered.

    In electrical installations AC usually used power capacitors. In them, electrodes are long strips of aluminum, lead or copper foil, separated by several layers of special (capacitor) paper impregnated with petroleum oils or synthetic impregnating liquids. The tapes of the foil 2 and paper 1 are wound into rolls (Fig. 185), dried, impregnated with paraffin, and placed in one or more sections in a metal or cardboard case. The required operating voltage of the capacitor is provided by series, parallel or series-parallel connections of individual sections.

    Ways to connect capacitors . Capacitors can be connected in series and in parallel.With consistent

    Application: Capacitors are used in almost all areas of electrical engineering.

    1. Capacitors (together with inductors and / or resistors) are used to build various circuits with frequency-dependent properties, in particular, filters, feedback circuits, oscillatory circuits, etc.

    2. With a fast discharge of a capacitor, a high power pulse can be obtained, for example, in flash units, electromagnetic accelerators, pulsed lasers with optical pumping, Marx generators, (GIN; GIT), Cockroft-Walton generators, etc.

    3. Since a capacitor is capable of maintaining a charge for a long time, it can be used as a memory element or an electrical energy storage device.

    4. Liquid level meter. Non-conductive fluid fills the space between the capacitor plates, and the capacitance of the capacitor varies with the level

    5. Accumulators of electric energy. In this case, the capacitor plates should be sufficiently constant values ​​of voltage and discharge current. In this case, the discharge itself must be significant in time.Currently, there are experimental development of electric vehicles and hybrids using capacitors. There are also some models of trams in which capacitors are used to power traction motors when driving along de-energized sections.

    Ticket 16. Dielectrics.

    Dielectrics (insulators) - substances that conduct poorly or do not conduct electric current at all. Dielectric materials include air, some gases, glass, plastics, various resins, many types of rubber.

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