Build an electromagnet and testing of its action. Plan-abstract lesson "Magnetic field coil with current

Plan - an abstract lesson in physics in grade 8 on the topic:

"Magnetic field coil with current. Electromagnets.

Laboratory work number 8 "Build an electromagnet and testing of its action."

Objectives lesson: To teach to collect the electromagnet from the finished parts and experienced by checking out, from which it depends on its magnetic action.

Tasks.

Educational:

1. Using the game form of activity in the lesson, repeat the basic concepts of the topic: a magnetic field, its features, sources, a graphic image.

2. Organize activities in pairs of permanent and replacement composition on the assembly of electromagnet.

3. Create organizational conditions for conducting an experiment to determine the dependence of magnetic properties at the conductor with a current.

Developing:

1. Ride the student skills of effective thinking: the ability to allocate the main thing in the material studied, the ability to compare the studied facts and processes, the ability to logically express their thoughts.

2. Ride the skills of working with physical equipment.

3. Ride the emotional-willed scope of students, when solving problems of varying degrees of complexity.

Educational:

1. Creating the conditions for the formation of such qualities as respect, independence and patience.

2. The formation of a positive "I - competence".

Cognitive. Highlight and formulate a cognitive goal. Build logical chains of reasoning.

Regulatory. They put a learning task based on the correlation that has already been learned, and what is still unknown.

Communicative. Communicate knowledge between members of the Group to make effective joint decisions.

Type of lesson: Lesson of methodological direction.

Problem learning technology and CSR.

Equipment for laboratory work:electromagnet collapsible with parts (designed to carry out frontal laboratory work on electricity and magnetism), source of TO-KA, retail, key, connecting wires, compass.

Demonstrations:

The structure and course of the lesson.

	Stage lesson	Tasks stage	Activity teacher	Activity student		Time
Motivational - estimated component
	Organizational stage	Psychological preparation for communication	Provides a favorable attitude.	Configured to work.	Personal

	Stage of motivation and actualization (definition of the lesson and joint activity).	Ensure activities to update the knowledge and determination of the lesson purposes.	Offers to play the game, and repeat the basic concepts of the topic. It offers to discuss the positional task and call the topic of the lesson, to determine the goal.	Trying to answer, solve the positional task. Determine the subject of the lesson and the goal.

Operational - executive component
	Studying a new material.	Promote the activities of students on an independent solution of tasks.	It offers to organize activities according to the proposed tasks.	Perform laboratory work. Work individually, in pairs. General-class work.	Personal, informative, regulatory
Reflective - Evaluation Component
	Control and self-test knowledge.	Remove the quality assimilation of the material.	It offers to solve the tasks.	Decide. Respond. Discuss.	Personal, informative, regulatory
	Summing up, reflection.	Adequate self-assessment of the individual, its capabilities and abilities, advantages and restrictions is formed.	Offers answer questions about the questionnaire "It's time to draw conclusions."	Respond.	Personal, informative, regulatory
	Feed homework.	Fastening the material studied.	Recording on the board.	Record in diary.	Personal

1. Repeat the basic concepts of the topic. Input testing.

The game "Continue offer."

Substances that attract iron objects are naked ... (magnets).

Conductor interaction with current and magnetic arrow
For the first time discovered the Danish scientist ... (Ersted).

Between the conductors with the current arise the strength of the interaction, which are called ... (magnetic).

The location of the magnet, in which the magnetic action is stronger than all, are called ... (magnet poles).

There is an electric shock around the conductor ...
(a magnetic field).

The source of the magnetic field serves ... (moving charge).

7. Lines, along which an axis is located in a magnetic field
Little magnetic arrows, called ... (by power magnetic lines).

The magnetic field around the conductor with current can be found, for example, ... (with a magnetic arrow or with iron sawdust).

9. Body, last time retaining their magnetic, are called ... (permanent magnets).

10. Poles of the magnet ..., and the variepetes - ... (repel,

attract

2. "Black box."

What is hidden in the box? Will learn if you understand what is being discussed in the story of the Dari "electricity in its applications." Presentation of a French magician in Algeria.

"On the scene there is a small windowed box with a handle on the lid. I causing a person from the audience. In response to my challenge, Arab of secondary growth was performed, but strong addition ...

"Come walk," I said, "and lift the box." Arab has bent, raised the box and asked arrogant:

- Nothing more?

"Wait a little bit," I answered.

Then take a serious look, I made an imperative gesture and uttered a solemn tone:

- You are now weaker than women. Try to raise the box again.

Slaya is not at all fasting my char, again took up the box, but this time the box has resistance and, despite the desperate efforts of Araba, remains still, as if chained to the place. Arab is strengthened to raise the box with such a force that would have enough for raising huge severity, but everything is in vain. Tired, breathing and burning from shame, he finally stops. Now he begins to believe in the power of the sorcerence. "

(From the book Ya. Perelman "Entertaining Physics. 2Dext".)

Question.What is the secret of the sorcery?

Discuss. Express your position. From the "black box" I pull out the coil, iron sawders and a galvanic element.

Demonstrations:

1) the action of the solenoid (coil without a core), on which a permanent current flows, on a magnetic arrow;

2) the action of the solenoid (coil with a core), according to which the constant current flows, anchor;

3) Attraction of iron sawdust with a core with a core.

Make the conclusion that it is electromagnet and formulate the purpose and task of the lesson.

3. Performing laboratory work.

The coil with an iron core inside is called electromagnet. Electromagnet is one of the main details of many technical devices. I suggest you to collect electromagnet and determine which it will depend on its magnetic action.

Laboratory work number 8

"Build an electromagnet and testing of its action"

Objective: Collect the electromagnet from the finished parts and to check on the experience, from which its magnetic action depends.

Guidelines for work

Task number 1. Make an electrical circuit of the battery, coil, key, connecting everything in series. Close the chain and with the help of a compass, determine the magnetic poles at the coil. Move the compass along the coil axis on such a distance, on which the magnetic field effect of the coil on the compass arrow is not significantly. Insert the iron core into the coil and refuel-let the effect of the electromagnet on the arrow. Take output.

Task number 2. Take two coils with an iron core, but with different numbers of turns. Check the poles with a compass. Determine the effect of electromagnets on the arrow. Compare and draw out.

Task number3. Insert the iron core into the coil and refuel-let the effect of the electromagnet on the arrow. Change the current strength in the chain using a row and watch the effect of the electromagnet on the arrow. Take output.

Work in static pairs.

1 row - Task number 1; 2 row - Task number 2; 3 row - Task number 3. Exchange tasks.

1 row - Task number 3; 2 row - Task number 1; 3 row - Task number 2.Exchange tasks.

1 row - Task number 2; 2 row - Task number 3; 3 row - Task number 1.Exchange tasks.

Work in parats of replacement composition.

At the end of the experiments are madeconclusions:

1. The electric current passes through the coil, the coil becomes a magnet;

2. Mognetic effect of the coil can be strengthened or loosen:
By changing the number of turns of the coil;

3. By changing the strength of the current passing by the coil;

4. Inside the coil of the iron or steel core.

Sheet selfpreparation selfrefutants I. selfquestion.

1. Input testing.The game "Continue offer."

1.__________________________

2.__________________________

3.__________________________

4.__________________________

5.__________________________

6.__________________________

7.__________________________

8.__________________________

9.__________________________

10._________________________

2. Laboratory work number 8 "An assembly of an electromagnet and testing of its action"

Purpose of work: Collect _______________ From the finished parts and on the experience, check, from which it depends on _____________.

Instruments and materials: galvanic element, retain, key, connecting wires, compass, parts for an electromagnet assembly.

Progress.

Task number 1.

Task number 2.

Task number 3.

Statement	I completely agree	Partially agree	Partially disagree	I do not fully agree
I purchased a lot of new information on the lesson.
I felt comfortable
Information received in the lesson, come in hand in the future
I received answers to all my questions about the lesson.
I will definitely share information with your friends received.

27.02.2014 9090 0

Purpose: find out students with the device of electromagnets and their use.Move students for overcoming difficulties in the process of mental activity, raise interest in physics.

Equipment for laboratory work: power supply, Reostat, key, connecting wires, compass, parts for an electromagnet assembly.

Demonstrations:device and principle of electromagnet; The use of electromagnets in an electrical call, electromagnetic: relay, telegraph.

During the classes

I.. Organizing time

II.. Reiteration.

Checking homework

IN the beginning of the lesson can be held a brief frontal survey: -. What magnetic phenomena are you known?

- What is the connection between the electric current and the magnetic field?

- What particles or bodies are the electric field? Whether the magnetic arrow is departed, if it is placed near the beam of moving particles: a) electrons; b) atoms; c) positive ions?

- What is called magnetic magnetic field line?

On the floor of the laboratory under the layer of linoleum laid a straight insulated wire. How to locate the wire and current directing in it without opening linoleum? Next, you can make out questions that have arisen when solving homework.

Device and principle of electromagnet

The coil on which the electric current flows is magnet and has two poles - North and South. With an increase in the current strength, the magnetic field of the coil is enhanced.

Strengthen the magnetic field of the coil can also be in another way: it is enough to enter the iron core inwards. Notify that this coil can be called electromagnet the teacher explains the students that the electromagnet is one of the main details of many technical devices: bell, telegraph, telephone, microphone, electromagnetic relay and dr.

III. Laboratory work

After a brief acquaintance with electromagnets and their applications pass toperforming laboratory work number 9. Work is performed according to the instruction of the textbook.

In the course of the laboratory work, it is necessary to draw the attention of students on how, knowing the current direction in the coil twists, determine the poles of the coil (electromagnet): if mentally "clasp" with the right hand the coilfrom current, placing four fingers in the direction of the current, then the bent thumb will indicate the north pole of the coil (direction of the magnetic field lines inside the coil).

Homework

1. § 58 textbooks; Questions to the paragraph.

2. Perform an exercise 28 (p. 136).

MOU "Kremmin Central Secondary School"

Plan - an abstract lesson in physics in grade 8 on the topic:

"Magnetic field coil with current. Electromagnets and their application. "

Teacher: Savostkov S.V.

Plan - Abstract lesson in physics in grade 8 on the topic:

"Magnetic field coil with current. Electromagnets and their application. "

Objectives lesson:

- training: To study the ways of gain and weakening the magnetic field of the coil with current; teach to determine the magnetic poles of the coil with a current; consider the principle of operation of the electromagnet and the field of its application; teach to collect electromagnet from
ready-made details and experienced by checking out where it depends on its magnetic action;

Developing: develop the ability to summarize knowledge, apply
knowledge in specific situations; Develop the skills of working from the device
mi; develop cognitive interest in the educational subject;

Educational: the upbringing of perpetuity, hard work, accuracy when performing practical work.

Type of lesson: combined (using ICT).

Equipment lesson: computers, author's presentation "Electromagnets".

Equipment for laboratory work: the electromagnet is collapsible with the details (designed to carry out frontal laboratory work on electricity and magnetism), current source, retail, key, connecting wires, compass.

Demonstrations:

1) the action of the conductor through which the constant

current, magnetic arrow;

2) the action of the solenoid (coil without a core), according to which a constant current flows, on a magnetic arrow;

attraction of iron sawdust with a nail to which on
motan wire connected to a constant source
current.

Movelesson

I. Organizing time.

Announcement of the lesson topics.

P. Actualization of reference knowledge(6 min).

"Continue offer"

Substances that attract iron objects are called ... (magnets).

Conductor interaction with current and magnetic arrow
for the first time discovered the Danish scientist ... (Oersted).

There are interaction forces that are called ... (Magnetic).

The location of the magnet, in which the magnetic action is strongest, are called ... (Magnet Poles).

There is an electric shock around the conductor ...
(a magnetic field).

The source of the magnetic field is ... (moving charge).

7. Lines along which an axis is located in a magnetic field
small magnetic arrows, called ... (power magicianthread lines).

The magnetic field around the conductor with the current can be detected, for example, ... (using a magnetic arrow or withusing iron sawdust).

If the magnet broke in half, then the first piece and the second
A piece of magnet has a pole ... (Northern -N. and southern -S.).

11.Telates, last time retaining their magnetization, are called ... (permanent magnets).

12. The Magnet Poles of the same name ... and a variepete - ... (repel, attract).

III. Main part. Studying a new material (20 min).

Slides number 1-2.

Frontal survey

Why to study a magnetic field can be used
iron sawdust? (In the magnetic field, the sawdust is magnetized and become magnetic arrows)

What is called magnetic magnetic field line? (Lines, along which the axis of small magnetic arrows are located in the magnetic field)

What is the concept of the magnetic field of the field? (With a cassette of magnetic lines conveniently depict magnetic fields graphically)

As on the experience, show that the direction of magnetic lines
associated with the direction of the current? (When changing the current direction in the conductor, all magnetic arrows rotate 180 about )

Slide No.

What unites these drawings (see slide)and how do they differ?

Slide number 4.

Is it possible to make a magnet that would have been only the North Pole? But only the South Pole? (Unable to domagnet, which would not have one of the poles).

If you break up a magnet into two parts, will these parts of magnets? (If you break the magnet to the part, then all itparts will be magnets).

What substances can magnify? (Iron, cobalt,nickel, alloys from these elements).

Slide№5

The magnets attached to the refrigerator became so popular that they are a collectibles object. So at the current moment the record according to the number of collected magnets belongs to Louise Greenfarb (USA). At the moment, a record of 35,000 magnets is registered in the Guinness Record.

Slide number 6.

- Is it possible to magnify the iron nail, a steel screwdriver, aluminum wire, copper coil, steel bolt? (Iron nail, steel bolt and steel screwdriver can be onmagnetic, but aluminum wire and copper coil onit is impossible to magnetize, but if you put an electric current on them, thenthey will create a magnetic field.)

Explain the experience shown in the drawings (See Slide).

Slide number 7.

Electromagnet

Andre Marie Ampere, conducting experiments with the coil (solenoid), showed the equivalence of its magnetic field of a permanent magnet field Solenoid(from Greek. Solen - Tube and Eidos - View) - Wire spiral, according to which the electric current is passed to create a magnetic field.

Studies of the magnetic field of circular current led the ampere to think that constant magnetism is explained by the existence of elementary circular currents that flowed particles from which magnets consist.

Teacher: Magnetism is one of the manifestations of electricity. How to create a magnetic field inside the coil? Is it possible to change this field?

Slides number 8-10.

Demonstrations performed by the teacher:

the action of the conductor through which constant proceeds
current, magnetic arrow;

solenoid action (coil without a core), according to which a constant current flows, on a magnetic arrow;

solenoid action (coil with a core) for which
personal current flows, on a magnetic arrow;

the attraction of iron sawdust with a nail to which the wire connected to the DC source is wound.

Teacher: The coil consists of a large number of turns of the wire wound on a wooden frame. When there is a current in the coil, the iron sawdust is attracted to its ends, when turning off the current, they disappear.

Include in the chain containing the coil, the row and with it, we will change the current strength in the coil. With an increase in the current strength, the magnetic field of the coil of the coil is enhanced, with a decrease - weakens.

The magnetic effect of the coil with current can be significantly increased, without changing the number of its turns and strength in it. To do this, we must introduce an iron rod inward (core). Iron, | Went inward coil, enhances its magnetic effect.

The coil with an iron core inside is called electromagnet. Electromagnet is one of the main details of many technical devices.

At the end of the experiments, conclusions are drawn:

if the coil passes the electric current, then the coil
becomes a magnet;

the magnetic effect of the coil can be strengthened or loosen:
by changing the number of turns of the coil;

changing current strength passing through the coil;

introducing an iron or steel core inwards.

Slide number 11.

Teacher: The windings of electromagnets are made of an isolated aluminum or copper wire, although there are superconducting electromagnets. The magnetic pipeline is made of magnetic-soft materials - usually from electrical or high-quality structural steel, cast steel and cast iron, iron phones and iron-coal alloys.

The electromagnet is a device, the magnetic field of which is created only when the electric current is proceeding.

Slide number 12.

Think and answer

Is it possible to call the wire by electromagnet wound on the nail? (Yes.)

What is the magnetic properties of an electromagnet depend on? (From
current forces, from the number of turns, from magnetic properties core, from the shape and size of the coil.)

3. The electromagnet was let the current, and then reduced it to
twice. How did the magnetic properties of the electromagnet change? (Decreased by 2 times.)

Slides number 13-15

1-y.pupil: William Rutchen (1783-1850) - An English Electric Engineer, created the first horseshoe-shaped electromagnet, capable of holding the load more of its own weight (200-gram electromagnet was able to hold 4 kg of iron).

The electromagnet, demonstrated by the end of May 23, 1825, looked like bent in the horseshoe, lacquered, iron rod 30 and a diameter of 1.3 cm, topped with one layer of isolated copper wire. The electromagnet kept 3,600 g and significantly exceeded the strength of the natural magnets of the same mass.

Joule, experimented with the very first magnet of the rod, managed to bring his lifting force to 20 kg. It was in the same 1825

Joseph Henry (1797-1878) - American physicist, improved electromagnet.

In 1827, J. Henry began to isolate no longer a core, but the wire itself. Only then it became possible to wind up the turns in several layers. J. Henry examined various wire winding methods to obtain an electromagnet. Created a magnet of 29 kg, holding a giant for the time weight - 936 kg.

Slides number 16-18.

2-y.pupil: Electromagnetic cranes, which can carry huge loads without fasteners, are applied at the factories. How do they do it?

Arc adhesive electromagnet holds anchor (iron plate) with suspended cargo. Rectangular electromagnets are designed for capturing and holding during the transportation of sheets, rails and other long cargo.

While there is a current in the winding of an electromagnet, no "iron" will not fall. But if the current in the winding for some reason will be interrupted, the accident is inevitable. And such cases were.

At one American plant, the electromagnet raised iron blanks.

Suddenly, at the power plant of the Niagara Falls, the current, something happened, the current in the winding of the electromagnet was disappeared; The mass of the metal fell out of the electromagnet and his whole severity fell on the head of the worker.

To avoid repetition of such accidents, as well as to save consumption of electrical energy, during electromagnets began to make special devices: after portable items raised by a magnet, the side of the side is lowered and tightly closed the durable steel spars, which then support the cargo, the current during Transportation is interrupted.

Electromagnetic traverses are used to move long cargo.

In seaports for overloading scrap metal, probably the most powerful round lifting electromagnets are used. Their mass reaches 10 tons, load capacity - up to 64 tons, and a tear-off force - up to 128 tons.

Slides number 19-22

3rd student: Basically, the scope of electromagnets is electrical machines and devices included in industrial automation systems into electrical installation equipment. Useful properties of electromagnets:

quickly demagnetize when the current is turned off,

it is possible to manufacture electromagnets of any size,

when working, you can adjust the magnetic action by changing the current strength in the chain.

Electromagnets are used in lifting devices, for cleansing coal from metal, for sorting different seed varieties, for molding iron parts, in tape recorders.

Electromagnets are widely used in the technique due to their wonderful properties.

Electromagnets Single-phase AC are intended for remote control by actuating mechanisms of various industrial and domestic purposes. Electromagnets with large lifting force are used on plants for carrying products from steel or cast iron, as well as steel and cast-iron chips, ingots.

Electromagnets are used in the telegraph, telephone, in an electrical call, electric motor, transformer, electromagnetic relay and in many other devices.

As part of various mechanisms, electromagnets are used as a drive to carry out the necessary progressive movement (rotation) of the working bodies of machines or to create deterrent. These are electromagnets of lifting machines, electromagnets couplings and brakes, electromagnets used in various starters, contactors, switches, electrical meters, and so on.

Slide №23

4th student: Brian Twighties, General Director of Walker Magnetics, proudly presents the world's largest suspension electromagnet. Its weight (88 tons) is about 22 tons exceeding the weight of the current winner of the Guinne-SA Books from the United States. Its carrying capacity is approximately 270 tons.

The world's largest electromagnet is used in Switzerland. The electromagnet of the 8-coal form consists of a core made of 6400 tons of low carbon steel, and an aluminum coil weighing 1100 tons. The coil consists of 168 turns attached to electric welding on the frame. The current by force of 30 thousand A, passing through the coil, creates a magnetic field with a capacity of 5 kilogauss. The sizes of an electromagnet, superior to the height of the 4-storey building, are 12x12x12 m, and the total weight is 7810 tons. The manufacture has gone larger than the metal than to build the Eiffel Tower.

The world's most difficult magnet has a diameter of 60 m and weighs 36 thousand tons. It was made for a synchrophasotron capacity of 10 TEV installed in the United Institute of Nuclear Research in Dubna, the Moscow region.

Demonstration: electromagnetic telegraph.

Fastening (4 min).

3 pollov on computers perform the work "Solvalkin" on the topic "Electromagnet" from the site
Slide No. 24.

What is called electromagnet? (Coil with iron core)

What methods can increase the magnetic effect of the coil with

current? (the magnetic effect of the coil can be strengthened:
by changing the number of turns of the coil, changing current strength passing by the coil, introducing an iron or steel core inwards.)

In which direction is the coil with a current,
hung on long thin conductors? What similarity
is it with a magnetic arrow?

4. For what purposes are electromagnets used at factories?

Practical part (12 min).

Slide number 25.

Laboratory work.

Fulfilling students of independently laboratory work number 8 "Build an electromagnet and testing of its action ", p.175 Textbook" Physics-8 "(author A3. Pyryshkin," Drop ", 2009).

Slay yudı №25-26

Summing up and setting estimates.

Vi. Homework.

2. Run a home research project "Motor for
minutes " (Instruction is issued to each student for work
at home, see Appendix).

Project "Motor for 10 minutes"

It is always interesting to observe the changing phenomena, especially if you are involved in creating these phenomena. Now we will collect the simplest (but actually working) an electric motor consisting of a power source, a magnet and a small coil of the wire, which we will also do ourselves. There is a secret that will make this set of items become an electric motor; The secret that is simultaneously smart and amazingly simple. That's what we need:

battery 1.5 V or battery;

holder with contacts for the battery;

1 meter wire with enamel insulation (diameter 0.8-1 mm);

0.3 meters of uninsulated wire (diameter 0.8-1 mm).

We will start with winding the coil, that part of the electric motor that will rotate. To make the coil sufficient smooth and round, wrap it on a suitable cylindrical framework, for example, on a AA battery.

Leaving free 5 cm wires from each end, we wock 15-20 turns on the cylindrical frame. Do not try especially tightly and smoothly wind the coil, a small degree of freedom will help the coil better to preserve its shape.

Now carefully remove the coil from the frame, trying to keep the resulting form.

Then wrap several times the free ends of the wire around the turns to preserve the shape, observing the new bonding turns to be exactly opposite each other.

The coil should look like this:

Now the time is the secret, the features that will make the motor work. It is a refined and non-obvious reception, and it is very difficult to detect when the motor works. Even people who know a lot about the work of the engines can be surprised by finding this secret.

Holding the coil vertically, put one of the free ends of the coil on the edge of the table. A sharp knife remove the upper half of the insulation from one free end of the coil (holder), leaving the untouched lower half. Do the same with the second end of the coil, observing the uninsulated ends of the wires to be directed up in two free ends of the coil.

What is the meaning of this reception? The coil will lie on two holders made of uninsulated wire. These holders will be attached to different ends of the battery so that the electrical current can pass from one holder through the coil to another holder. But it will only happen when uninsulated half of the wires are lowered down, touching holders.

Now it is necessary to make support for the coil. it
just the turns of the wires that support the coil and allow it to rotate. They are made of uninsulated wire, so
as, besides supporting the coil, they should deliver it electric current. Just wrap every piece of uninsulated pro
water around a small nail - Get the desired part of our
engine.

The basis of our first motor will be the battery holder. It will be a suitable base also because when the battery is installed, it will be sufficiently heavy for the motor is not trembling. Collect five parts together, as shown in the picture (at the beginning without a magnet). Put on top of the battery magnet and gently push the coil ...

If everything is done correctly, the coil will start to rotate quickly!

I hope that everything will work from the first time. If still the motor did not earn, carefully check all electrical connections. Does the coil rotate freely? Is it easy to closely located magnet? If not enough, install additional magnets or cut wire holders.

When the motor earn, the only thing to pay attention to - so that the battery does not overheat, as the current is large enough. Just remove the coil - and the chain will be torn.

The model of your motor will demonstrate classmates and teacher at the next physics lesson. Let the comments of classmates and the assessment of your project teacher will become an incentive for further successful design of physical instruments and knowledge of the surrounding world. I wish you success!

Laboratory work number 8

"Build an electromagnet and testing of its action"

Purpose of work:collect the electromagnet from the finished parts and to check the experience, from which its magnetic action depends.

Instruments and materials:battery of three elements (or batteries), retaint, key, connecting wires, compass, parts for an electromagnet assembly.

Guidelines for work

1. Make an electrical circuit of the battery, coil, risostat and key, connecting everything sequentially. Close the chain and with the help of a compass, determine the magnetic poles at the coil.

Move the compass along the coil axis on such a distance, on which the magnetic field effect of the coil on the compass arrow is insignificant. Insert the iron core into the coil and move the effect of the electromagnet on the arrow. Take output.

Change the current strength in the chain using a row and watch the effect of the electromagnet on the arrow. Take output.

Collect an arcuate magnet from ready-made details. Electromagnet coils connect between themselves sequentially so that different magnetic poles are obtained at their free ends. Check the poles with a compass. Determine with a compass, where the northern is located, and where is the South Pole of the magnet.

History of electromagnetic telegraph

IN The world electromagnetic telegraph was invented by the Russian scientist and diplomat Pavl Lvovich Schilling in 1832. Being on a business trip in China and other countries, he acutely felt the need for a high-speed communication. In the telegraph apparatus, they use the magnetic arrow property to be deflected in one or the other direction depending on the direction of the current passing through the wire.

The shilling apparatus consisted of two parts: transmitter and receiver. Two telegraph devices were connected to the conductions among themselves and with an electrical battery. The transmitter had 16 keys. If you click on the White Keys, the current walked one way, if on black - to another. These current pulses reached the serum wires, which had six coils; Near each coil on the threads, two magnetic arrows and a small disk were suspended (see Left Fig.). One side of the disk was stained with black paint, another - white.

Depending on the current direction in the coils, the magnetic arrows turned into one direction or the other side, and the telegraph taking signal, saw the black or white mugs. If the current in the coil did not flow, the disk was visible to the edge. For its apparatus, shilling has developed an alphabet. Schillling devices worked on the world's first telegraph line built by the inventor in St. Petersburg in 1832, between the Winter Palace and the Cabinets of Some Ministers.

In 1837, American Samuel Morse designed a telegraph device that records signals (see Right Fig.). In 1844, the first telegraph line was opened, equipped with Morse apparatus between Washington and Baltimore.

Electromagnetic Telegraph Morse and the signal recording system developed in the form of points and dashes were widespread. However, Morse apparatus had serious disadvantages: the transmitted telegram must be decrypted and then write; Mala transfer rate.

P the world in the world, the letterpressure invented the Russian scientist Boris Semenovich Jacobi in 1850. This apparatus had a printing wheel, which rotated at the same speed as the wheel of another apparatus installed on the adjacent station (see the bottom Fig.). On the rims of both wheels, letters, numbers and signs wetting with paint were engraved. Under the wheels of the devices, electromagnets had, and between the anchors of the electromagnets and wheels were stretched by paper tapes.

For example, you need to pass the letter "A". When on both wheels, the letter A was located at the bottom, the key was pressed on one of the devices and the chain closed. Anchors of electromagnets attracted to cores and pressed paper tapes to the wheels of both devices. On the tapes at the same time, the letter A. To send any other letter, you need to "catch" the moment when the desired letter will be on the wheels of both devices below, and press the key.

What are the conditions for proper transmission in the Jacobi apparatus? The first - wheels should rotate at the same speed; The second - on wheels of both devices the same letters should occupy the same positions at any time in space. These principles were used in the telegraph devices of the last models.

Many inventors worked on the improvement of telegraph communications. There were telegraph devices that transferred and took tens of thousands of words per hour, but they are complex and cumbersome. A lot of distribution at one time received teletypes - letterpressing telegraph devices with a keyboard like a typewriter. Currently, the telegraphic devices are not used, their telephone, cellular and Internet communications displaced them.

Explanatory note

... №6 by topic tok Magnetic field. Magnetic field Direct tok. Magnetic lines. 1 55. Magnetic field coils from tokom. Electromagnets and them With ...

in Physics program for grades 7-9 educational institutions authors of the program: EM Gutnik, AV Peryshkin M .: Bustard. 2007 textbooks (included in the federal list)

Program

... №6 by topic "The work and power of electric tok»1 Electromagnetic phenomena. (6 h) 54 Magnetic field. Magnetic field Direct tok. Magnetic lines. 1 55. Magnetic field coils from tokom. Electromagnets and them With ...

Order No. from "" 201. Working program in physics for the basic level of study of physics of the main school class 8

Working programm

... physics. Diagnostics by Repeated material 7. class. Diagnostic work Section 1. Electromagnetic phenomena Subject ... magnetic field coils from tokom from the number of turns, from strength tok in coil, from the presence of a core; application electromagnets ...

Laboratory work number 8 _____________________ Date of an electromagnet assembly and its testing. Purpose: Collect the electromagnet from the finished parts and to check the experience, from which it depends on its magnetic action. Equipment: power source, resistor, switch, connecting wires, a compass (magnetic needle), the arc-shaped magnet, ammeter, range, parts for assembling the solenoid (coil and core). Safety regulations. Carefully read the rules and lay down in what they undertake to perform them. Caution! Electricity! Make sure the insulation of the conductors is not broken. When conducting experiments with magnetic fields, you should shoot with the hands of the clock and remove the mobile phone. Rules have been familiar with the rules (a), I undertake to perform. ________________________ Signature of the student's work. 1. Make the electrical circuit from the power supply, coil, risostat, ammeter and key, connecting them sequentially. Draw a chain assembly scheme. 2. Close the chain and use the magnetic arrow to determine the poles at the coil. Measure the distance from the coil before the L1 arrow and the current strength I1 in the coil. record measurement results in Table 1. 3. Move the arrow along the magnetic axis of the coil to a distance L2, in which the magnetic field coil for magnetic action arrow slightly. Measure this distance and current strength I2 in the coil. The measurement results are also record in table 1. Table 1 L1 coil without the core, see I1, A L2, see I2, A 4. Insert the iron core to the coil and observe the action of the electromagnet on arrow. Measure the distance L3 from the coil before the arrow and the current strength I3 in the coil with the core. record measurement results in table 2. 5. Move the arrow along the magnetic axis of the coil core to a distance L4, on which the magnetic field coil for magnetic action arrow slightly. Measure this distance and current strength I4 in the coil. The measurement results are also record in table 2. Table 2 Coil L3 core cm I3, A L4, see I4, A 6. Compare the results obtained in claim 3 and claim 4. Make output ______________ ________________________________________________________________________________________________________________________________________ 7. Adjust the rheostat via the current strength in the circuit and observe the action of the electromagnet on arrow. Make a conclusion: _____________________________ ____________________________________________________________________ ____________________________________________________________________ 8. Collect an arcuate magnet from ready-made details. Electromagnet coils connect between themselves sequentially so that different magnetic poles are obtained at their free ends. Check the poles with a compass, determine where the northern is located, and where is the southern pole of an electromagnet. Sketch the magnetic field produced by you electromagnet Test questions: 1. What has similarities with the current in the coil with a magnetic needle? __________ ________________________________________________________________________________________________________________________________________ 2. Why is the action of a magnetic coil, on which there is a current, amplified by introducing the iron core in it? _______________________________________ ____________________________________________________________________________________________________________________________________________________________________________________________________________ 3. What is called an electromagnet? For what purposes are electromagnets (3-5 examples) use? ______________________________________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ________ 4. Is it possible to connect coils of a horseshoe-shaped electromagnet so that at the ends of the coil turned out the same poles? ________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 5. What will be the pole at the pointy end of the iron nail, if his hat to bring the south pole of the magnet? Explain the phenomenon ___________ ____________________________________________________________________________________________________________________________________________________________________________________________________

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Plan - an abstract lesson in physics in grade 8 on the topic:

"Magnetic field coil with current. Electromagnets.

Laboratory work number 8 "Build an electromagnet and testing of its action."

Objectives lesson: To teach to collect the electromagnet from the finished parts and experienced by checking out, from which it depends on its magnetic action.

Tasks.

Educational:

1. Using the game form of activity in the lesson, repeat the basic concepts of the topic: a magnetic field, its features, sources, a graphic image.

2. Organize activities in pairs of permanent and replacement composition on the assembly of electromagnet.

3. Create organizational conditions for conducting an experiment to determine the dependence of magnetic properties at the conductor with a current.

Developing:

2. Ride the skills of working with physical equipment.

3. Ride the emotional-willed scope of students, when solving problems of varying degrees of complexity.

Educational:

1. Creating the conditions for the formation of such qualities as respect, independence and patience.

2. The formation of a positive "I - competence".

Cognitive. Highlight and formulate a cognitive goal. Build logical chains of reasoning.

Regulatory. They put a learning task based on the correlation that has already been learned, and what is still unknown.

Communicative. Communicate knowledge between members of the Group to make effective joint decisions.

Personal.ABOUT sonated, respectful and friendly attitude towards another person, his opinion.

Type of lesson: Lesson of methodological direction.

Problem learning technology and CSR.

Demonstrations:

The structure and course of the lesson.

	Stage lesson	Tasks stage	Activity teacher	Activity student		Time
Motivational - estimated component
	Organizational stage	Psychological preparation for communication	Provides a favorable attitude.	Configured to work.	Personal

	Stage of motivation and actualization (definition of the lesson and joint activity).	Ensure activities to update the knowledge and determination of the lesson purposes.	Offers to play the game, and repeat the basic concepts of the topic. It offers to discuss the positional task and call the topic of the lesson, to determine the goal.	Trying to answer, solve the positional task. Determine the subject of the lesson and the goal.

Operational - executive component
	Studying a new material.	Promote the activities of students on an independent solution of tasks.	It offers to organize activities according to the proposed tasks.	Perform laboratory work. Work individually, in pairs. General-class work.	Personal, informative, regulatory
Reflective - Evaluation Component
	Control and self-test knowledge.	Remove the quality assimilation of the material.	It offers to solve the tasks.	Decide. Respond. Discuss.	Personal, informative, regulatory
	Summing up, reflection.	Adequate self-assessment of the individual, its capabilities and abilities, advantages and restrictions is formed.	Offers answer questions about the questionnaire "It's time to draw conclusions."	Respond.	Personal, informative, regulatory
	Feed homework.	Fastening the material studied.	Recording on the board.	Record in diary.	Personal