Lab No. 8 _____________________

the date

Assembling the electromagnet and testing its operation.

Target: assemble an electromagnet from ready-made parts and test by experience what its magnetic effect depends on.

Equipment: power supply, rheostat, key, connecting wires, compass (magnetic needle), arcuate magnet, ammeter, ruler, parts for assembling an electromagnet (coil and core).

Safety regulations.Read the rules carefully and sign that you agree to follow them..

Carefully! Electricity! Make sure that the insulation of the conductors is not broken. When conducting experiments with magnetic fields, you should take off your watch and put away your mobile phone.

I have read the rules and agree to abide by them. ________________________

Student Signature

Working process.

1. Make up an electrical circuit from a power source, a coil, a rheostat, an ammeter and a key, connecting them in series. Draw a circuit assembly diagram.

1. Close the circuit and use the magnetic needle to determine the poles of the coil.

Measure the distance from the coil to the needle L 1 and current I 1 in the coil.

Record the measurement results in table 1.

1. Move the magnetic needle along the axis of the coil to such a distance L2,

on which the effect of the magnetic field of the coil on the magnetic needle is negligible. Measure this distance and current I 2 in a coil. Also record the measurement results in Table 1.

Table 1

Coil without core	L 1 cm	I 1, A	L 2 cm	I 2, A

4. Insert the iron core into the coil and observe the action

Electromagnet on the arrow. measure distance L 3 from the coil to the arrow and

Current strength I 3 in a core coil. Record the measurement results in

Table 2.

1. Move the magnetic needle along the axis of the core coil to

Distance L 4 , on which the action of the magnetic field of the coil on the magnetic

Arrow slightly. Measure this distance and current I 4 in the coil.

Also record the measurement results in Table 2.

table 2

Coil core	L 3 cm	I 3, A	L 4 cm	I 4, A

1. Compare the results obtained in paragraph 3 and paragraph 4. Do conclusion: ______________

____________________________________________________________________

1. Use a rheostat to change the current in the circuit and observe the effect

Electromagnet on the arrow. Do conclusion: _____________________________

____________________________________________________________________

____________________________________________________________________

1. Assemble the arcuate magnet from prefabricated parts. Electromagnet coils

connect together in series so that opposite magnetic poles are obtained at their free ends. Check the poles with a compass, determine where the north and where is the south pole of the electromagnet. Sketch the magnetic field of the electromagnet you received.

TEST QUESTIONS:

1. What is the similarity between a coil with current and a magnetic needle? __________ ________________________________________________________________________________________________________________________________

1. Why does the magnetic effect of a coil carrying current increase if an iron core is introduced into it? ___________________________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________

1. What is an electromagnet? For what purposes are electromagnets used (3-5 examples)? ________________________________________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ________

1. Is it possible to connect the coils of a horseshoe electromagnet so that the ends of the coil have the same poles? ________________________
   ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

1. What pole will appear at the pointed end of an iron nail if the south pole of a magnet is brought near its head? Explain the phenomenon ___________ __________________________________________________________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Laboratory work No. 8 _____________________ date Assembling the electromagnet and testing its operation. Purpose: to assemble an electromagnet from ready-made parts and to test by experience what its magnetic effect depends on. Equipment: power supply, rheostat, key, connecting wires, compass (magnetic needle), arcuate magnet, ammeter, ruler, parts for assembling an electromagnet (coil and core). Safety regulations. Read the rules carefully and sign that you agree to follow them. Carefully! Electricity! Make sure that the insulation of the conductors is not broken. When conducting experiments with magnetic fields, you should take off your watch and put away your mobile phone. I have read the rules and agree to abide by them. ____________________________ Student Signature Progress. 1. Make an electrical circuit from a power source, a coil, a rheostat, an ammeter and a key, connecting them in series. Draw a circuit assembly diagram. 2. Close the circuit and use the magnetic needle to determine the poles of the coil. Measure the distance from the coil to the arrow L1 and the current I1 in the coil. Record the measurement results in Table 1. 3. Move the magnetic needle along the coil axis to a distance L2 at which the effect of the coil's magnetic field on the magnetic needle is negligible. Measure this distance and the current I2 in the coil. Record the measurement results in Table 1 as well. Table 1 Coil without core L1, cm I1, A L2, cm I2, A 4. Insert the iron core into the coil and observe the action of the electromagnet on the needle. Measure the distance L3 from the coil to the arrow and the current I3 in the core coil. Record the measurement results in Table 2. 5. Move the magnetic needle along the axis of the coil with the core to a distance L4 at which the effect of the magnetic field of the coil on the magnetic needle is insignificant. Measure this distance and the current I4 in the coil. Record the measurement results in Table 2 as well. Table 2 Coil with core L3, cm I3, A L4, cm I4, A 6. Compare the results obtained in paragraph 3 and paragraph 4. Conclude: ______________ ________________________________________________________________________________________________________________________________ 7. Change the current strength in the circuit with the help of a rheostat and observe the action of the electromagnet on the arrow. Make a conclusion: _____________________________ __________________________________________________________________________ ________________________________________________________________________ 8. Assemble the arcuate magnet from prefabricated parts. Connect the coils of an electromagnet in series with each other so that opposite magnetic poles are obtained at their free ends. Check the poles with a compass, determine where the north and where is the south pole of the electromagnet. Sketch the magnetic field of the electromagnet you received. CONTROL QUESTIONS: 1. What is the similarity between a coil with a current and a magnetic needle? __________ ________________________________________________________________________________________________________________________________ 2. Why does the magnetic effect of the coil through which the current flows increase if an iron core is introduced into it? _______________________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________ 3. What is called an electromagnet? For what purposes are electromagnets used (3-5 examples)? ________________________________________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ________ 4. Is it possible to connect the coils of a horseshoe electromagnet so that the ends of the coil have the same poles? ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 5. What pole will appear at the pointed end of an iron nail if the south pole of a magnet is brought near its head? Explain the phenomenon ___________ __________________________________________________________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

150.000₽ prize fund 11 documents of honor Evidence of publication in the media

Plan - summary of a lesson in physics in grade 8 on the topic:

The magnetic field of a coil with current. Electromagnets.

Laboratory work No. 8 "Assembling an electromagnet and testing its operation."

Lesson Objectives: teach how to assemble an electromagnet from ready-made parts and experimentally check what its magnetic effect depends on.

Tasks.

Educational:

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

2. organize activities in pairs of permanent and replaceable composition for the assembly of an electromagnet.

3. create organizational conditions for conducting an experiment to determine the dependence of the magnetic properties of a current-carrying conductor.

Developing:

1. develop students' skills of effective thinking: the ability to highlight the main thing in the material being studied, the ability to compare the studied facts and processes, the ability to logically express their thoughts.

2. develop skills in working with physical equipment.

3. to develop the emotional-volitional sphere of students in solving problems of varying degrees of complexity.

Educational:

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

2. to promote the formation of a positive "I - competence".

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

Regulatory. They set a learning task based on the correlation of what has already been learned and what is still unknown.

Communicative. Share knowledge among group members to make effective joint decisions.

Lesson type: methodological lesson.

Problem-Based Learning Technology and CSR.

Equipment for laboratory work: collapsible electromagnet with parts (intended for frontal laboratory work on electricity and magnetism), current source, rheostat, key, connecting wires, compass.

Demos:

Structure and course of the lesson.

	Lesson stage	Stage tasks	Activity teachers	Activity student		Time
Motivational - indicative component
	Organizational stage	Psychological preparation for communication	Provides a favorable mood.	Getting ready for work.	Personal
	The stage of motivation and actualization (determining the topic of the lesson and the joint goal of the activity).	Provide activities to update knowledge and determine the objectives of the lesson.	Offers to play a game and repeat the basic concepts of the topic. Offers to discuss the positional task and name the topic of the lesson, determine the goal.	They are trying to answer, to solve a positional problem. Determine the theme of the lesson and the purpose.
Operational - executive component
	Learning new material.	To promote the activity of students in independent problem solving.	Offers to organize activities according to the proposed tasks.	Perform laboratory work. Work individually, in pairs. General work.	Personal, cognitive, regulatory
Reflective - evaluative component
	Control and self-examination of knowledge.	To identify the quality of assimilation of the material.	Offers to solve problems.	Decide. Answer. Discuss.	Personal, cognitive, regulatory
	Summing up, reflection.	An adequate self-assessment of the individual, his capabilities and abilities, advantages and limitations is formed.	Offers to answer the questions of the questionnaire "It's time to draw conclusions."	Answer.	Personal, cognitive, regulatory
	Submission of homework.	Consolidation of the studied material.	Writing on the board.	Recorded in a diary.	Personal

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

Game "Continue the offer."

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

Interaction of a conductor with current and a magnetic needle
first discovered by a Danish scientist ... (Oersted).

Interaction forces arise between conductors with current, which are called ... (magnetic).

The places of the magnet, in which the magnetic effect is most pronounced, are called ... (magnet poles).

Around a conductor with electric current there is ...
(a magnetic field).

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

7. Lines along which the axes are located in a magnetic field
small magnetic arrows are called ... (magnetic lines of force).

The magnetic field around a conductor with current can be detected, for example, ... (using a magnetic needle or using iron filings).

9. Bodies that retain their magnetization for a long time are called ... (permanent magnets).

10. The same poles of the magnet ..., and the opposite - ... (repel,

are attracted

2. "Black box".

What is hidden in the box? You will find out if you understand what is at stake in the story from Dari's book "Electricity in its applications." Representation of a French magician in Algiers.

“On the stage is a small ironed box with a handle on the lid. I call a stronger person from the audience. In response to my challenge, an Arab of medium height, but strong build, came forward ...

- Approach the court, - I said, - and lift the box. The Arab bent down, picked up the box and arrogantly asked:

- Nothing else?

“Wait a little,” I replied.

Then, assuming a serious air, I made an imperious gesture and said in a solemn tone:

- You are now weaker than a woman. Try lifting the box again.

The strong man, not at all afraid of my charms, again took hold of the box, but this time the box resisted and, despite the desperate efforts of the Arab, remained motionless, as if chained to the place. The Arab tries to lift the box with enough force to lift a huge weight, but all in vain. Tired, out of breath and burning with shame, he finally stops. Now he's starting to believe in the power of sorcery."

(From the book of Ya.I. Perelman "Entertaining physics. Part 2".)

Question. What is the secret of sorcery?

Discuss. Express their position. From the "Black Box" I take out a coil, iron filings and a galvanic cell.

Demos:

1) the action of a solenoid (a coil without a core), through which a direct current flows, on a magnetic needle;

2) the action of the solenoid (coil with a core), through which a direct current flows, on the armature;

3) attraction of iron filings by a coil with a core.

They conclude what an electromagnet is and formulate the purpose and objectives of the lesson.

3. Performing laboratory work.

A coil with an iron core inside is called electromagnet. An electromagnet is one of the main parts of many technical devices. I suggest you assemble an electromagnet and determine what its magnetic effect will depend on.

Lab #8

"Assembling an electromagnet and testing its operation"

The purpose of the work: to assemble an electromagnet from finished parts and experimentally check what its magnetic effect depends on.

Instructions for work

Task number 1. Make an electrical circuit from a battery, a coil, a key, connecting everything in series. Close the circuit and use the compass to determine the magnetic poles of the coil. Move the compass along the axis of the coil to a distance at which the effect of the magnetic field of the coil on the compass needle is negligible. Insert the iron core into the coil and observe the action of the electromagnet on the needle. Make a conclusion.

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

Task number 3. Insert the iron core into the coil and observe the effect of the electromagnet on the arrow. Use the rheostat to change the current in the circuit and observe the effect of the electromagnet on the arrow. Make a conclusion.

They work in static pairs.

1 row - task number 1; 2 row - task number 2; 3 row - task number 3. They exchange tasks.

1 row - task number 3; 2 row - task number 1; 3 row - task number 2.They exchange tasks.

1 row - task number 2; 2 row - task number 3; 3 row - task number 1.They exchange tasks.

Work in pairs of shifts.

At the end of the experiments,findings:

1. if an electric current passes through the coil, then the coil becomes a magnet;

2.The magnetic action of the coil can be strengthened or weakened:
by changing the number of turns of the coil;

3. changing the strength of the current passing through the coil;

4. Inserting an iron or steel core into the coil.

Sheet myself training, myself checks and myself estimates.

1. Entrance testing.Game "Continue the offer."

1.__________________________

2.__________________________

3.__________________________

4.__________________________

5.__________________________

6.__________________________

7.__________________________

8.__________________________

9.__________________________

10._________________________

2. Laboratory work No. 8 "Assembling an electromagnet and testing its operation"

The purpose of the work: to assemble _______________ from finished parts and to verify by experience what _____________ action depends on.

Devices and materials: a galvanic cell, a rheostat, a key, connecting wires, a compass, parts for assembling an electromagnet.

Working process.

Task number 1.

Task number 2.

Task number 3.

Statement	I completely agree	Partially agree	Partially disagree	Completely disagree
I have acquired a lot of new information on the topic of the lesson
I felt comfortable
The information received in the lesson will be useful to me in the future.
I received answers to all my questions on the topic of the lesson.
I will definitely share this information with my friends.

27.02.2014 9090 0

Target: To acquaint students with the device of electromagnets and their application.To encourage students to overcome difficulties in the process of mental activity, to cultivate interest in physics.

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

Demos:device and principle of operation of an electromagnet; the use of electromagnets in an electric bell, electromagnetic: relay, telegraph.

During the classes

I. Organizing time

II. Repetition.

Checking homework

AT At the beginning of the lesson, you can conduct a short frontal survey: -. What magnetic phenomena do you know?

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

- What particles or bodies are affected by an electric field? Will the magnetic needle deviate if it is placed near a beam of moving particles: a) electrons; b) atoms; c) positive ions?

- What is a magnetic field line called?

A straight insulated wire is laid on the floor of the laboratory under a layer of linoleum. How to determine the location of the wire and the direction of the current in it without opening the linoleum? Next, you can analyze the questions that arose when solving homework problems.

The device and principle of operation of an electromagnet

A coil carrying an electric current is magnet and has two poles - north and south. As the current increases, the magnetic field of the coil increases.

It is possible to strengthen the magnetic field of the coil in another way: it is enough to introduce an iron core inside the coil. Saying that such a coil can be called electromagnet, the teacher explains to the students that an electromagnet is one of the main parts of many technical devices: a bell, a telegraph, a telephone, a microphone, an electromagnetic relay, and others

III. Laboratory work

After a brief introduction to electromagnets and their applications, to performing laboratory work No. 9. The work is performed according to the instructions of the textbook.

In the course of laboratory work, it is necessary to draw students' attention to how, knowing the direction of the current in the turns of the coil, determine the poles of the coil (electromagnet): if you mentally “grasp” the coil with your right hand with current, placing four fingers in the direction of the current, then the bent thumb will indicate the north pole of the coil (the direction of the magnetic field lines inside the coil).

Homework

1. § 58 textbook; questions for the paragraph.

2. Do exercise 28 (p. 136).

Measurement of voltage in various parts of the electrical circuit.

Determining the resistance of a conductor using an ammeter and a voltmeter.

Objective: learn how to measure the voltage and resistance of a circuit section.

Devices and materials: power supply, spiral resistors (2 pcs.), ammeter and voltmeter, rheostat, key, connecting wires.

Instructions for work:

1. Assemble a circuit consisting of a power source, a key, two spirals, a rheostat, an ammeter connected in series. The rheostat engine is located approximately in the middle.
2. Draw a diagram of the circuit you have assembled and show on it where the voltmeter is connected when measuring the voltage on each spiral and on two spirals together.
3. Measure the current in the circuit I, the voltages U 1, U 2 at the ends of each spiral and the voltage U 1.2 in the section of the circuit consisting of two spirals.
4. Measure the voltage at the rheostat U p. and on the poles of the current source U. Enter the data in the table (experiment No. 1):

experience number	№1	№2
Current I, A
Voltage U 1, V
Voltage U 2, V
Voltage U 1.2 V
Voltage U p. , AT
Voltage U, V
Resistance R 1, Ohm
Resistance R 2, Ohm
Resistance R 1.2, Ohm
Resistance R p. , Ohm

1. Using a rheostat, change the resistance of the circuit and repeat the measurements again, recording the results in a table (experiment No. 2).
2. Calculate the sum of the voltages U 1 +U 2 on both spirals and compare with the voltage U 1.2. Make a conclusion.
3. Calculate the sum of the voltages U 1.2 + U p. And compare with the voltage U. Make a conclusion.
4. From each individual measurement, calculate the resistances R 1 , R 2 , R 1.2 and R p. . Draw your own conclusions.

Lab #10

Checking the laws of parallel connection of resistors.

Objective: check the laws of parallel connection of resistors (for currents and resistances). Remember and write down these laws.

Devices and materials: power supply, spiral resistors (2 pcs.), ammeter and voltmeter, key, connecting wires.

Instructions for work:

1. Carefully consider what is indicated on the panel of the voltmeter and ammeter. Determine the limits of measurements, the price of divisions. Use the table to find the instrumental errors of these devices. Write down the data in a notebook.
2. Assemble a circuit consisting of a power source, a key, an ammeter and two spirals connected in parallel.
3. Draw a diagram of the circuit you have assembled and show on it where the voltmeter is connected when measuring the voltage at the poles of the current source and on the two spirals together, as well as how to connect the ammeter to measure the current in each of the resistors.
4. After checking by the teacher, close the circuit.
5. Measure the current in the circuit I, the voltage U at the poles of the current source and the voltage U 1.2 in the section of the circuit consisting of two spirals.
6. Measure the currents I 1 and I 2 in each spiral. Enter the data in the table:

1. Calculate the resistances R 1 and R 2, as well as the conductivity γ 1 and γ 2, of each spiral, the resistance R and the conductivity γ 1.2 of the section of two parallel-connected spirals. (Conductivity is the reciprocal of resistance: γ=1/ R Ohm -1).
2. Calculate the sum of the currents I 1 + I 2 on both spirals and compare with the current strength I. Draw a conclusion.
3. Calculate the sum of the conductivities γ 1 + γ 2 and compare with the conductance γ. Make a conclusion.

1. Evaluate direct and indirect measurement errors.

Lab #11

Determination of the power and efficiency of the electric heater.

Devices and materials:

Clock, laboratory power supply, laboratory electric heater, ammeter, voltmeter, key, connecting wires, calorimeter, thermometer, scales, beaker, vessel with water.

Instructions for work:

1. Weigh the inner beaker of the calorimeter.
2. Pour 150-180 ml of water into the calorimeter and lower the coil of the electric heater into it. The water should completely cover the coil. Calculate the mass of water poured into the calorimeter.
3. Assemble an electrical circuit consisting of a power source, a key, an electric heater (located in the calorimeter) and an ammeter connected in series. Connect a voltmeter to measure voltage across the electric heater. Draw a schematic diagram of this circuit.
4. Measure the initial temperature of the water in the calorimeter.
5. After checking the circuit by the teacher, close it, noting the moment in time it was turned on.
6. Measure the current through the heater and the voltage at its terminals.
7. Calculate the power generated by the electric heater.
8. After 15 - 20 minutes after the start of heating (note this point in time), measure the water temperature in the calorimeter again. At the same time, it is impossible to touch the electric heater spiral with a thermometer. Turn off the circuit.
9. Calculate useful Q - the amount of heat received by water and the calorimeter.
10. Calculate Q total, - the amount of heat released by the electric heater for the measured period of time.
11. Calculate the efficiency of a laboratory electric heating installation.

Use the tabular data from the textbook "Physics. 8th grade." edited by A.V. Peryshkin.

Lab #12

Study of the magnetic field of a coil with current. Assembling the electromagnet and testing its operation.

C spruce work: 1. explore the magnetic field of the coil with current using a magnetic needle, determine the magnetic poles of this coil; 2. assemble an electromagnet from ready-made parts and test its magnetic effect by experience.

Devices and materials: laboratory power supply, rheostat, key, ampemeter, connecting wires, compass, parts for assembling an electromagnet, various metal objects (carnations, coins, buttons, etc.).

Instructions for work:

1. Make an electrical circuit from a power source, a coil, a rheostat and a key, connecting everything in series. Close the circuit and use the compass to determine the magnetic poles of the coil. Perform a schematic drawing of the experiment, indicating on it the electric and magnetic poles of the coil, and depicting the appearance of its magnetic lines.
2. Move the compass along the axis of the coil to a distance at which the effect of the magnetic field of the coil on the compass needle is negligible. Insert the steel core into the coil and observe the action of the electromagnet on the arrow. Make a conclusion.
3. Use the rheostat to change the current in the circuit and observe the effect of the electromagnet on the arrow. Make a conclusion.
4. Assemble the arcuate magnet from prefabricated parts. Connect the magnet coils in series so that opposite magnetic poles are obtained at their free ends. Check the poles with a compass. Use a compass to determine where the north and where is the south pole of the magnet.
5. Using the resulting electromagnet, determine which of the bodies proposed to you are attracted to it, and which are not. Write down the result in a notebook.
6. In the report, list the applications of electromagnets known to you.
7. Make a conclusion from the work done.

Lab #13

Determination of the refractive index of glass

Objective:

Determine the refractive index of a glass plate shaped like a trapezoid.

Devices and materials:

Trapezium-shaped glass plate with plane-parallel edges, 4 sewing pins, protractor, square, pencil, sheet of paper, foam lining.

Instructions for work:

1. Lay a sheet of paper on the foam pad.
2. Place a plane-parallel glass plate on a sheet of paper and trace its contours with a pencil.
3. Lift up the foam pad and, without moving the plate, stick pins 1 and 2 into the sheet of paper. In this case, you need to look at the pins through the glass and stick pin 2 so that pin 1 is not visible behind it.
4. Move pin 3 until it is in line with the imaginary images of pins 1 and 2 in the glass plate (see Fig. a)).
5. Draw a straight line through points 1 and 2. Draw a straight line through point 3 parallel to line 12 (Fig. b)). Connect the points O 1 and O 2 (Fig. c)).

6. Draw a perpendicular to the air-glass interface at point O 1. Specify the angle of incidence α and the angle of refraction γ

7. Measure the angle of incidence α and the angle of refraction γ using

Protractor. Write down the measurement data.

1. Use a calculator or Bradis tables to find sin a and sing . Determine the refractive index of glass n Art. relative to air, considering the absolute refractive index of air n woz.@ 1.

.

1. You can determine n Art. and in another way, using Fig. d). To do this, it is necessary to continue the perpendicular to the air-glass interface as far down as possible and mark an arbitrary point A on it. Then continue the incident and refracted rays with dashed lines.
2. Drop from point A the perpendiculars to these extensions - AB and AC.Ð AO 1 C = a , Ð AO 1 B = g . Triangles AO 1 B and AO 1 C are rectangular and have the same hypotenuse O 1 A.
3. sin a \u003d sin g \u003d n st. =
4. Thus, by measuring AC and AB, one can calculate the relative refractive index of glass.
5. Estimate the error of the measurements made.