Lesson topic: Laboratory work"Measurement of voltage in various parts of the electrical circuit"
Lesson Objectives:
Subject: to consolidate the ZUN of students on the topic "Electric current", to continue the formation of the concept of voltage in students, the skills and abilities to assemble the simplest electrical circuits, to form practical skills for measuring voltage.
Metasubject: develop the ability to observe, compare and generalize the results of the experiment; develop the ability to logically express their thoughts.
Personal: continue to develop interest in the study of physics, to intensify cognitive activity, educate: accuracy in the performance of work, organization, discipline, the ability to work in a microgroup.
Lesson type: combined.
Lesson repetition of previously studied material and laboratory work.
Equipment for the lesson: computer, video projector, interactive whiteboard, power supply, voltmeter, spiral-resistors-2pcs., key, connecting wires.
Lesson steps:
Message about the topic and purpose of the lesson
Knowledge update
Hello, are you ready for the lesson? So let's start.
In the last lesson, we went through the topic " electrical voltage».
Did we measure it?
Therefore, the topic of today's lesson, what will we have?
Voltage measurement
Let me add to the topic: on various parts of the chain. slide 1.
Open your workbooks and write down the topic of the lesson.
Today we have to perform laboratory work "Measurement of voltage in various parts of the circuit." But first, let's recall and repeat the previously studied material on the topic of electric current. This will help you get the job done.
Repetition of the studied material
Peer review in pairs. Slide 2.
1.What is electric current? (Ordered motion of charged particles)
2. From which pole of the current source and to which is it customary to consider the direction of the current? (From "+" to "-")
3. Remember the elements of the circuit and their symbol.
4.What does the voltage show? ( Voltage shows how much work an electric field does when moving a unit positive charge from one point to another)
5. What is the formula for calculating voltage? (U= A| q)
6.Voltage unit? (V-VOLTS)
7. What is the name of the device for measuring voltage? (Voltmeter)
8. How is a voltmeter turned on to measure voltage in a circuit section?
(1. Include in the electrical circuit only in parallel. (The clamps of the voltmeter are connected to those points of the circuit between which it is necessary to measure the voltage)
2. Observe the polarity. (The voltmeter is connected to the circuit using two terminals on the device. One of the terminals of the voltmeter has a “+” sign, the other has a “-”. The terminal with the “+” sign must be connected to the wire coming from the positive pole of the current source)
3. Can be connected to the circuit without load.)
1.3 Testing knowledge and skills
What is the name of the symbols for the components of the electrical circuit.
Slide 3 (Magic window)
Remember the rules for including a voltmeter in email. chain. slide 4.
I propose to assemble on the board an electrical circuit consisting of 2 el. lamps connected in series, a key, a current source and a voltmeter that measures the voltage on lamp 1. (on lamp 2, on a current source, on 2 lamps)
And you draw a diagram of this circuit in your notebook. Student B will draw an email diagram. chains on the board.
On the diagram, show the direction of the electric current and indicate on the diagram the polarity of the terminals of the voltmeter.
Physical education (passive):
In the physics classroom, on one of the walls there are images of three pigeons of different colors. To calm music, students are invited to fix their attention on one of them, then close their eyes, slowly turn their heads and mentally transfer the image of a dove to the opposite wall. The same is done with the rest of the images of doves. This provides rest for the eyes and brain.
Performing laboratory work
Close workbooks. We open notebooks for laboratory work (p. 8).
What is the name of the job? (Voltage measurement in various parts of the electrical circuit.)
What is the purpose of the work? (Measure the voltage at the section of the circuit consisting of two spirals connected in series, and compare it with the voltage at the end of each spiral)
What tools and materials are needed to do the job? (current source, spiral-resistors-2 pcs., voltmeter, key, connecting wires)
Take a voltmeter with a measurement limit of 6 V.
When doing work, observe TB:
TB when working with electrical measuring instruments.slide 5
Carefully! Electricity! Make sure that the insulation of the conductors is not broken. When assembling the electrical circuit, arrange the wires carefully, and clamp the lugs tightly with terminals.
Assemble electrical circuits, switch them, install and repair electrical devices only when the power source is disconnected. Perform observations and measurements, being careful not to touch live parts that are energized or bare wires. Do not turn on the circuit without the teacher's permission. There should be no foreign objects on the table. Protect appliances from falling. Avoid extreme loads of measuring instruments.
Guys, when doing laboratory work, we observe TB, but for what?
High voltage is life-threatening. The human and animal body conducts electricity very well, because it contains ionic solutions. The human body is a conductor. Passing through it, an electric current can cause damage to vital organs, and sometimes death.
Guys, let's find out together with you what voltage is dangerous for a person and What will happen to the person which will be next to the fallen bare cable,
under high voltage? Find the answer to this question on the Cool Physics website.
In all laboratory experiments where a voltmeter is used, you must first assemble the circuit without it, and then connect the voltmeter to the section where the voltage is measured. The voltmeter can be switched from one section to another without disassembling the remaining sections of the circuit.
To take readings from a voltmeter, you need to determine the division value of the device.
Results. What conclusion did you come to?
W: We have learned how to measure electrical voltage in various parts of the circuit. The voltage across two resistors connected in series is equal to the sum of the voltages across each resistor. U \u003d U 1 + U 2.
We found out that the electric field does a different job of moving a unit charge in our resistors.
- Why is it important to learn new physical quantity voltage?
W: High voltage is life-threatening. Caution must be observed when working with small voltages. Depending on the conditions, even a small voltage can be dangerous.
Reflection. There are three identical cardboard squares 3x3cm in size on the table. There are three lever scales on the teacher's table. There are signs on the scales: “I”, “We”, “Business”. Left bowl weights means "poorly", right – "Okay". At the end of the lesson, students independently place their squares on one or another bowl of each scale. Thus, the result of the work of students in the lesson and their self-esteem becomes clearly visible.
Homework.
Repeat paragraphs 39-41, exercise 16 (1,2).
According to laboratory experience come up with a problem and solve it.
Each student receives a mark for completing the laboratory work after checking the notebooks by the teacher.
State budget professional educational institution
Arzamas Commercial Technical College
electrical engineering classes
on the topic: "Classification of measuring instruments"
Executor:
MM. Stepanova,
teacher
special disciplines
Plan
Introduction
Lesson project
Psychological and pedagogical characteristics of the group
ZUN diagnostics
Open class project
Introspection of the lesson
Literature
Applications
Introduction
In any field of knowledge, measurements are extremely important, but they are especially important in electrical engineering. A person feels mechanical, thermal, light phenomena with the help of his sense organs. We, although approximately, can estimate the size of objects, the speed of their movement, the brightness of luminous bodies. For a long time, this is how people studied the starry sky. But you and I react in exactly the same way to a conductor whose current is 10 mA or 1 A (that is, 100 times more). We see the shape of the conductor, its color, but our senses do not allow us to estimate the magnitude of the current. In the same way, we are completely indifferent to the magnetic field created by the coil, electric field between the capacitor plates. Medicine has established a certain effect of electric and magnetic fields on the human body, but we do not feel this effect, and the magnitude electro magnetic field we cannot evaluate. The only exceptions are very strong fields. But here, too, an unpleasant tingling, which can be noticed when walking the eye of a high-voltage transmission line, will not allow us to even approximately estimate the magnitude of the electrical voltage in the line. All this forced physicists and engineers to use electrical measuring instruments from the first steps in the study and application of electricity.
Instruments are the eyes and ears of an electrical engineer. Without them, he is deaf and blind and completely helpless. Millions of electrical measuring instruments are installed in factories and research laboratories. Each apartment also has a measuring device - an electric meter. Indications (signals) of electrical measuring instruments are used to evaluate the operation of various electrical devices and the state of electrical equipment, in particular the state of insulation.
Electrical measuring instruments are characterized by high sensitivity, measurement accuracy, reliability and ease of execution. The success of electrical instrumentation led to the fact that other industries began to use its services. Electrical methods began to be used to determine dimensions, speeds, masses, and temperatures. There was even an independent discipline "Electrical measurements of non-electric quantities".
The modern level of industry cannot do without electrical measurements. In order to ensure the normal operation of electrical equipment, it is necessary to measure current, voltage, resistance, power, the amount of energy consumed and a number of other electrical characteristics.
All these measurements are made using electrical measuring instruments. Only knowing the methods of electrical measurements and the properties of electrical measuring instruments can control the operation of various electrical installations, achieve energy and fuel savings, and ensure the uninterrupted operation of electrical machines.
Lesson project
Psychological and pedagogical characteristics of the group
In the group 15-22 EREE - 25 students. Age 16 - 17 years.
The team in the group is formed. A favorable psychological climate has developed. At the emotional and interpersonal level, the group is close-knit, friendly, efficient; there are clear leaders.
The group has an average level of awareness, the ability to generalize, analyze, analyze and synthesize, apply the acquired skills in solving problems and performing tasks. practical work.
According to the level of development and training, the group is multi-level.
The first level - creative - includes 20% of students in the group who have a good stock of knowledge, can operate with concepts, analyze, independently acquire knowledge, and apply it in practice.
The second level - applied - includes 30% of students. They can reproduce material that is not very large in volume, answer the questions set out, but they can analyze the material only according to questions or an algorithm.
The third level includes 50% of students who do not have the ability to concentrate, which require an individual approach and additional classes.
In general, the students of the group feel comfortable.
ZUN diagnostics
students should know the concept of a measuring instrument, the division value of the instrument, the measurement limit of the instrument, the measurement error;
be able to use simple measuring instruments;
be able to carry out the simplest measurements and evaluate the measurement result, taking into account errors.
The project of an open lesson in the discipline
"Electrical and Electronics"
Group : 15-22 EREO
Speciality : 13.02.11 Technical operation and maintenance of electrical and electromechanical equipment (by industry)
Teacher: Stepanova M.M.
the date of the : 01/17/2017
Topic of the lesson : "Classification of measuring instruments"
Class type : lesson
Lesson type : combined
Pedagogical technology: developmental learning technology with elements project activities
Lesson objectives:
Educational:
to familiarize students with the types of electrical measuring instruments;
form an idea of the principles of operation of various electrical measuring systems;
give an idea of the errors of electrical measuring instruments;
to teach how to organize their own activities, choose standard methods for performing educational tasks, evaluate their effectiveness and quality;
to provide students with the opportunity to independently acquire knowledge by analyzing educational material.
Educational :
Promote development
the ability to apply the acquired knowledge in practice;
ability to analyze and draw conclusions;
intellectual abilities (thinking, memory, speech);
skills of individual and collective activity;
public speaking skills.
Educational :
to promote understanding of the essence and significance of the topic;
create conditions for the formation of a sense of responsibility, communicative competence;
contribute to the education of students' sustainable interest in discipline and teamwork skills.
Interdisciplinary connections: physics mathematics, electric cars and devices, the basics of technical operation and maintenance of electrical and electromechanical equipment; electrical and electromechanical equipment.
Qualification requirements:
Students should know:
concepts: measurement, measuring device, division value of the device, measurement limit of the device, measurement error;
classification of electrical measuring instruments;
the principle of operation of measuring instruments.
Students should be able to:
operate with concepts;
work with textbooks;
present the studied material in the form of tables;
repeat and summarize what has been learned;
calculate measurement errors.
Means of education:
Multimedia projector, personal computer, presentation, video, measuring instruments
Didactic material: individual list of students' assignments, tasks, test
Literature:
| № p/p | During the classes | Theoretical substantiation of the teacher's activity | Projected student activity | Time |
| Greeting students, checking those present, checking readiness for the lesson, wish successful work, psychological attitude to the lesson. | They greet the teacher, check the readiness for the lesson, tune in to work. | |||
| Updating of basic knowledge | Prepare students for learning new material, consolidating knowledge on the material covered (solution of test tasks, frontal survey). Create conditions for the development of communicative competence | decide test tasks provide answers to teacher questions | ||
| Motivation learning activities, the message of the topic and purpose of the lesson | Contribute to the increase cognitive interest to the topic under study Designation of the topic, acquaintance with the objectives of the lesson. | Students listen carefully, write down the topic and epigraph of the lesson. | ||
| Presentation of material on the topic: The concept of a measuring instrument Types of measuring instruments The principle of operation of measuring instruments Instrument error Classification of measuring instruments | The presentation of the teacher provides a better perception, emphasizes the key points of the material being studied. Group work in the study of the fifth question develops independent work skills, improves the effectiveness of learning Students' messages "Digital Measuring Instruments", "Logometers" Watching a video expands the horizons of students, arouses interest in the topic under study, and contributes to the formation of imaginative thinking. | Participate in the discussion of the questions posed, analyze, draw conclusions, keep records in individual task sheets, fill out the table Listen to the messages of their classmates, take notes on their own Extract information from a fragment of an educational film | ||
| Generalization and systematization of the studied material | Establishment of the primary level of assimilation of the material through solving problems focused on the most important points | Solve problems, give self-assessment of knowledge. | ||
| Homework | Ad homework instructions for its implementation. | Students listen, write down homework | ||
| Summing up the lesson | Thanks students, analyzes their work, announces grades | Students listen to grades |
Introspection of the lesson
This lesson was held in a group where students of different levels of ability, therefore, when planning the lesson, I used good cognitive abilities individual students who have good memory and mental skills. Students with other abilities participated in the work with concepts, i.e. in reproductive activities.
A combined lesson on the topic "Classification of measuring instruments" is held after studying the topic "Measuring instruments" in order to systematize knowledge. It is based on the knowledge, skills and abilities of students obtained in the classroom in physics. This lesson provides the formation of interest in electrical science, which will be the necessary basis for the study of subsequent topics and subjects.
The whole lesson consists of 7 stages, each of which had its own educational tasks, but these stages are interconnected. Each stage continued the previous one, and the lesson turned out to be complete and complete. The volume of the necessary material was carefully selected, therefore, it corresponded to the time of the lesson, which was compiled and conducted compactly, as a whole, where the next stage followed from the previous one.
The volume of the necessary material was carefully selected, therefore, it corresponded to the time of the lesson, which was compiled and conducted compactly, as a whole, where the next stage followed from the previous one.
The main emphasis in the lesson was on the development of the mental activity of students.
6.7. When systematizing and generalizing knowledge, the following methods were used:
visual;
verbal: the introductory word of the teacher and problematic questions intensified the mental activity of students, historical thinking;
used inductive and deductive methods;
partial search activity;
Information Technology.
8. The lesson was attended by independent work of students - both individual and group. The tasks were of a reproductive and developmental nature, at different levels (differentiated and activity approaches were used). Each type of work was preceded by a teacher's briefing.
9. Knowledge control took place throughout the lesson: when updating knowledge, during a conversation, conclusions, etc.
10. High performance was ensured by activating and simplifying the material, with the help of information technologies, as well as through various teaching methods: problem questions, filling in tables, using visualization, alternating types of work. The psychological climate was provided by the encouragement of students.
11. At the lesson there was a creative, search atmosphere, cooperation and mutual understanding of the teacher and students. Students at the lesson were active, participated with pleasure in all types of educational activities.
12. Homework was given on time, feasible, followed by instructions.
13. The goals set by the teacher have been achieved. Half of the students in the group received positive marks.
Literature
Sindeev Yu.G. Electrical engineering with the basics of electronics - Rostov-on-Don: Phoenix, 2009.
Lotereychuk E.A. Theoretical basis electrical engineering - M .: ID Forum - INFRA, 2009.
Danilov I.A., Ivanov P.M. General electrical engineering with the basics of electronics. – M.: higher school, 2000.
Fundamentals of industrial electronics / Ed. V. G. Gerasimov. – M.: high school, 2002
Applications
Attachment 1
INDIVIDUAL TASK LIST
ON ELECTRICAL ENGINEERING AND ELECTRONICS
Topic:
"Classification of measuring instruments"
"Science begins when one begins to measure."
D. I. Mendeleev
Task 1. Define:
Electrical measuring instruments are
Analog devices are
________________________________________________________________________________________________________________________________________________ ________________________________________________________________________
Digital devices are
________________________________________________________________________________________________________________________________________________ ________________________________________________________________________
Task 2. Fill in the diagram:
Classification of scales of measuring instruments
By uniformity of graduation:
By graduation:
By zero position:
Task 3. Define:
The division price is ________________________________________________________________________________________________________________________________________________________________________________________________________________________
Task 4. Fill in the table:
| Types of errors |
||
| Absolute | Relative | Reduced |
Task 5. Fill in the table:
| Classification of measuring instruments: |
|||
| By appointment | By type of current | According to the degree of accuracy | According to the principle of action |
Task 6. Fill in the table:
| Systems of electrical measuring instruments: |
||||||
| Instrumentation system | Symbol | Operating principle | Device | Advantages | disadvantages | |
| magnetic | ||||||
| electric | ||||||
| electro-dynamic | ||||||
| induction | ||||||
Task 7. Fill in the table:
| Symbol on the scales: |
|
| Designation | Decryption |
Task 8. Solve the problems:
The highest current that can be measured with an ammeter is 15 A, accuracy class 4. Determine the absolute error of the device.
Given: Solution:
When measuring the current strength I \u003d 4A, an ammeter with a scale of O - 10A was used and it showed 4.1 A. Calculate the basic (conducted) error of the device.
Ministry of Education and Science of the Krasnodar Territory
state budgetary professional educational institution of the Krasnodar Territory
"Kropotkin College of Technology and Railway Transport"
Methodological development of the lesson
"Cooking First Meals"
Developed
English teacher
Voloshina Natalya Ivanovna
Kropotkin, 2015
Lesson topic: Cooking first courses
Lesson Objectives:
Educational:
to teach how to make technological maps of first courses;
learn to build a dialogue, monologues, ask questions and answer them;
learn to use new words in colloquial speech lexical units on this topic;
be able to apply the acquired knowledge in practice.
Developing:
to develop students' cognitive and professional interest in the technologies of cooking first courses;
to promote the formation of cognitive interest in the chosen profession;
develop cognitive, creative activity, develop memory, logical thinking, imagination.
Educational:
to cultivate a sense of self-confidence, a creative approach to the task, interest and desire for knowledge of the profession;
education of work culture;
develop the ability to work in a team (in pairs, subgroups, individually).
The task of the lesson: to generalize and systematize ZUN on the topic studied.
Lesson type: integrated.
Methodical methods: advanced training;
presentation work;
work with the didactic material;
partially - search;
reproductive;
explanatory - illustrative.
Methodological support: personal computer, multimedia projector, didactic material.
Interdisciplinary connections: " English language”,“ Technology ”,“ Commodity food products”, “Physiology of nutrition, sanitation and hygiene”.
Pedagogical technologies: cooperation technology, ICT, developmental education technology, health-saving technologies, problem-based learning.
Used Books:
Anfimov N.A., Tatarskaya L.L. "Cooking"., M.: Publishing Center "Academy" 2005.
Collection of recipes for people and culinary products., M .: Publishing Center "Academy" 2005.
Kachurina T.A. "Cooking" workbook., M .: Publishing Center "Academy" 2008.
Internet resources:
[ Download the file to see the link ]; [Download the file to view the link]
Final word teacher. slide-13
teacher:
- You "ve learned a lot of about cooking the first courses. I hope that this knowledge will be useful to you in your future profession and working. Our lesson is over. Thank you for the good work.
goodbye.
Application - 1
Cooking the first courses
The students' answers:
Student 1:
Borsch is the Ukrainian national dish. Soup is prepared on the bone broth, mushroom broth, vegetarian.
Traditional lunch in the Ukraine started with the borsch. It so happened that on the table, but bread and lard with garlic, mistress [
m
str
s] and there was nothing to put, but if it was borsch - consider that the dinner was very good.
Student-2:
Pickle is a soup with pickles. One hundred years ago, the pickle was not called soup, it was... a pie.
In the books of N. Gogol can be found: "pickle - chicken pot pie, buckwheat [
b
kwi
t] cereal [
s
·
r
·
·l], in the filling is added to the brine , chopped eggs".
The main word "brine," that is, a solution of salt, or liquid [
l
kw
d] generated [
·
en
re
t] during pickling cucumbers or pickled cabbage. The word "pickle" is a native Russian. Pickle-dish vintage
v
nt
·
·], only it was called before "Kala". It was cooked with eggs, meat, chicken, kidney [
k
dn
·], and not only on cucumber brine, but lemon water and served with cakes and pies.
Student 3:
" Shchee is the meat soup, not the usual prohibitively
bad meat soup, and wonderful Russian dish with fat from various [
v
·
r
·
s] meats, eggs, sour cream and herbs . In fact, it seems to me, impossible to eat anything after shcheer" , - Knut Hamsun (Norwegian writer)
Application-2
Cooking the first courses
technology card
"Ukrainian borsch"
product name
Gross weight
net weight
beetroot
150
120
Cabbage fresh or pickled
100
80
Potatoes
213
160
carrots
50
40
Onion
36
30
tomato puree [
pj
·
re
·]
30
30
Garlic
4
3
vegetable oil
20
20
Wheat flour
6
6
Shpik
10,4
10
sugar
10
10
Vinegar 3% [
v
n
g
·]
10
10
sweet pepper
27
20
Brother
700
700
Output
-
1000
Application - 3
Cooking the first courses
physical exercises.
One, two - take a cabbage. One, two - take the cabbage.
Three, four - quickly trim. Three, four - clean it.
Five, six - finely cut. Five, six, chop.
Seven, eight - put it into the pan. Seven, eight - we'll throw it into the pan. Nine, ten - mu soup is ready. Nine, ten, my soup is ready.
Do it again.
Application-4
Cooking the first courses
Match the English proverbs with Russian equivalents.
1) The appetite comes with eating.
a) There is no arguing about tastes.
2) After dinner sleep a while, after supper walk a mile.
b) An apple a day and don't know doctors.
3) An apple a day keeps the doctor away.
c) Appetite comes with eating.
4) Don't live to eat, but eat to live.
d) Sleep a little after dinner, walk a mile after dinner.
5) Taste differ.
e) Not to live to eat, but to eat to live.
Application - 5
Cooking the first courses
technology card
Solyanka
product name
Gross weight
net weight
technology card
"Soup kharcho"
product name
Gross weight
net weight
Application-5
Cooking the first courses
technology card
"Pickle Leningrad"
product name
Gross weight
net weight
technology card
Okroshka
product name
Gross weight
net weight
Application-5
Cooking the first courses
The standard answers
technology card
"Pickle Leningrad"
product name
Gross weight
net weight
Potatoes
200
150
Rice
15
15
carrots
25
20
Parsley (root),
7
5
Onion
12
10
Pickles
35
30
tomato puree
15
15
Butter
10
10
The brother
350
350
Products: rice, potatoes, carrots, butter, parsley (root), the broth, onion, pickles, tomato puree.
technology card
Okroshka
product name
Gross weight
net weight
Beef
109
80
Bread kvass
250
350
green onions
27
30
cucumbers
75
60
Potatoes
68
50
Radishes
5
5
Prepared mustard
2
2
Sour cream
15
15
Products: sour cream, sugar, cucumbers, beef, potatoes, bread kvass, eggs, prepared mustard, green onion, radishes.
Application-5
Cooking the first courses
The standard answers
technology card
Solyanka
product name
Gross weight
net weight
Beef
55
40
Boiled ham
25
20
Sausages
22
20
Kidney beef
60
50
Onion
50
40
Pickles
50
30
Potatoes
80
60
tomato puree
25
25
Butter
12
12
The brother
350
350
Sour cream
30
30
Products: butter, beef, pickles, sour cream, boiled ham, the broth, potatoes, kidney beef, tomato puree, onion, sausages.
technology card
"Soup kharcho"
product name
Gross weight
net weight
Rice
36
35
Onion
50
40
Butter
20
20
tomato puree
15
15
The spicy sauce
15
15
Garlic
4
3
Parsley (green)
20
15
Spices
1
1
Products: tomato puree, parsley (green), rice, butter, spices, onion, the spicy sauce, garlic.
Application-6
Cooking the first courses
Divide the words into three columns
Potatoes, beef, bread kvass, rice, beets, fresh cabbage, carrots, green onions, cucumbers, parsley (root), vegetable oil, onion, eggs, cucumbers, tomato puree.
borsch
Pickle
okroshka
potatoes - potatoes
beef
beets
rice groats - rice
bread kvass - bread kvass
fresh cabbage - cabbage fresh
carrots - carrots
green onion - green onion
parsley (root) - parsley (root)
fresh cucumbers - cucumbers
vegetable oil
onion - onion
tomato puree - tomato puree
pickled cucumbers - pickles
eggs
The standard answers
borsch
Pickle
okroshka
potatoes
potatoes
beef
beetroot
rice
bread kvass
fresh cabbage
carrots
green onions
carrots
parsley (root)
cucumbers
vegetable oil
onion
potatoes
tomato puree
pickles
eggs
Application-7
Cooking the first courses
The dialogue -1.
- How are you? I haven't seen for ages.
- I'm OK.
- I want my mother to make a surprise to prepare the potato soup with meatballs. You study at the “Cook” faculty [
fzhk
lt
·] help me, please. What products need I buy?
- You need to buy the following: minced meat , potatoes, onions,....
- When the broth comes to a boil, how long does it need to boil?
-10 minutes.
Thanks I go for groceries
gr
·
s
r
·].
- Good - bye.
- Good-bye.
The dialogue - 2.
-Hello.
- Hi.
How did you spend your summer vacation?
- Very well. I was at my grandma.
- What were you treated with?
- My grandmother excellent cooks a country cabbage soup.
- Wow! What dish is this?
- Shchee is a national Russian dish.
- What made is it?
- It is prepared from fresh sauerkraut [
sa
·
kra
t] sauerkraut, sorrel [
s
r
l] sorrel and spinach [
sp
n
·
·], and sometimes from young nettles .
- Is it tasty?
- Yes, of course. Come to me and I'll treat you its
- Bye.
- Bye.
13 PAGE \* MERGEFORMAT 141915
The purpose of the lesson: to form students' understanding of the practical use of laws and theories; how the action of a magnetic field on a loop with current is used in electrical measuring instruments.
During the classes
Checking homework by the method of individual survey and problem solving
1. Characteristics of the magnetic field - magnetic flux(answer on the board)
2. Ampère's law. Get formula. (answer on the board)
3. Determining the direction of the Ampere force using the left hand rule. (answer on the board)
4. Solve problems No. 844, 842 (on the board)
Learning new material
The action of a magnetic field on an electric current is used in the device of electrical measuring instruments. They are a class of devices used to measure quantities: current, voltage, frequency, capacitance, resistance, inductance ...
Electrical measuring instruments are used in industry, energy, scientific field, in everyday life. Electrical measuring instruments are classified according to different criteria.
For example, by Units of measured values. This can be seen on the scale of the device, where there is a Latin letter (A, V, W ...) or the full name is indicated.
The second important feature of the devices is Type of current: direct or variable.
The third distinguishing feature is Accuracy class, starting from 0.05 to 4.
The accuracy class shows the absolute accuracy of the device and its basic measurement error. During operation, the reliability and ergonomics of the devices play a decisive role. 
The internal structure of the devices differs in the types of systems. There is a class of devices Electrostatic system: electrometers, electrostatic voltmeters.
Instrument class magnetoelectric system, where the interaction of a magnet with a current is used. 
The device of the devices of this system should be considered in detail, since most of the devices used in physics lessons are of this system.
Common devices are electromagnetic system, which use the retraction of the core into a coil with current.
Electrodynamic system instrumentation uses Interaction of currents. Wattmeters are most often manufactured using such a system.
Consolidation of the studied material
- What instruments are classified as electrical measuring equipment?
In what areas are electrical measuring instruments used?
How are electrical appliances classified?
How are the devices of the magnetoelectric system arranged and measured?
Methodical development of a lesson in physics « Electrical measuring instruments»
Topic: "Electrical measuring instruments"
Lesson Objectives:
Educational :
consider with students the device of electrical measuring instruments;
repeat the concept of the Lorentz force, determine on what quantities it depends;
repeat the rule of the left hand; determining the direction of the Lorentz force vector using the left hand rule
experimentally observe the action of the Lorentz force;
learn to apply this knowledge in the course of solving problems.
Educational :
to promote the development of the cognitive interest of students through the observation of the action of the Lorentz force.
to form students' understanding of the practical use of laws and theories; how the action of a magnetic field on a loop with current is used in electrical measuring instruments.
Educational :
to educate students in discipline, attention, accuracy when taking notes in a notebook;
to cultivate in students patience, willpower, diligence in the course of solving problems;
contribute to the formation of the scientific worldview of students;
Lesson type: Combined
Lesson equipment:
Teacher's workstation
Bar magnet, ammeter, voltmeter, multimeter, resistor, connecting wires, switch (key), galvanometer.
During the classes
Hello guys. Sit down. Who is absent today?
In today's lesson, we will check D / Z, repeat the material of the last lesson, Let's explore a new topic.
Checking homework.
1. What is the induction of the magnetic field in which a conductor with an active part length of 5 cm is affectedis there a force of 50 mN? Current in the conductor 25 A. Conductorlocated perpendicular to the magnetic field.
2. With what force does a magnetic field act with an induction of 10 mT on a conductor in which the current strength is 50 A, if the length of the active part
3. Frontal survey questions:
What is the modulus of the magnetic induction vector?
In what units is magnetic induction measured?
Define the concept of lines of magnetic induction.
What does it consist of salient feature lines of magnetic induction?
Why do the lines of induction of the magnetic field created by a coil with current have almost the same configuration as the lines of induction of a strip permanent magnet?
Which pole of a magnet is called the north pole; southern?
Why does a magnetic field act on a magnetic needle?
Formulate Ampère's law. Write down its mathematical expression.
How is the Ampere force oriented relative to the direction of the current and the vector of magnetic induction?
State the left hand rule. How to determine the direction of the Ampère force using the left hand rule. (answer on the board)
Obtaining the formula for the Ampere Force and the Lorentz Force (answer at the blackboard)
Evaluation of students' answers.
Explanation of the new topic.
The topic of our lesson“Electrical measuring devices. The action of a magnetic field on a moving charge. Lorentz Force" Write it down.
Conversation. Orienting action magica filament field on a current-carrying circuit is used in electricalmeasuring instruments of the magnetoelectric system - ammeters and voltmeters.
.
Measuring device magnetoelectrical system is arranged followingblowing way. On thelightweight aluminum frame2
straight charcoal with attached arrow to her 4
coil is wound.The frame is fixed on two axle shafts00".
In the equilibrium position, it is held by two thin spiral springs 3.
Elastic forces with one hundredrons of springs that return kacarcass in a position of equilibrium, aboutproportional to the angle of deflection of the arrowski from the equilibrium position. Kathe carcass is placed between the polespermanent magnetM with tips special shaped kami. Insidecoil located soft iron cylinder1.
Such a constructtion provides radial onthe rule of magnetic induction lines in the area where the coil turns are located. As a resulttata at any position of the coilthe forces acting on it from the magnetic field are maximumand at a constant currentus. Vectors 
And - portrayforces acting on the coil from the side of the magnetic field and turning it. The coil with current rotates until the elastic forces from the side of the spring balance the forces acting on the frame from the side of the magnetic field. By increasing the current strength by 2 times, we will find that the arrow turns through an angle twice as large, etc. This is because the forces acting on the coil from the magnetic field are directly proportional to the current strength:F
m
~
I
.
Thanks to this, it is possible to determine the current strength by the angle of rotation of the coil, if the device is calibrated. To do this, you need to establish which angles of rotationand arrows correspond to knowncurrent values.
The same device can measure voltage. To do this, you need to calibrate the deviceso that the angle of rotation of the arrowcorresponded to certain voltage values. In addition, the resistance of the voltmeter should be much greater than the resistance of the ammeter.
The teacher demonstrates an ammeter and a voltmeter to the students.
Be sure to look inside the measuring device and find all the elements of its device that were discussed.
Students come to the teacher's table and examine the instruments.
Consolidation of knowledge.
How is the measuring device of the magnetoelectric system arranged?
Why magnetic forces, acting on the conductors of the coil of the device, do not depend on the angle of rotation of the coil?
What keeps the frame from rotating in a magnetic field?
How is an ammeter different from a voltmeter?
Additional material.
Electrical measuring instruments are used in industry, energy, scientific field, in everyday life. Electrical measuring instruments are classified according to different criteria.
For example, byunits of measured values . This can be seen on the scale of the device, where there is a Latin letter (A, V, W ...) or the full name is indicated.
The second important feature of the devices istype of current: direct or variable .
The third distinguishing feature isaccuracy class , starting from 0.05 to 4.
The accuracy class shows the absolute accuracy of the device and its basic measurement error. During operation, the reliability and ergonomics of the devices play a decisive role.
The internal structure of the devices differs in the types of systems. There is a class of deviceselectrostatic system: electrometers, electrostatic voltmeters.
Instrument classmagnetoelectric system, where magnet interaction is used
1. Homogeneous magnetic field inductionB = 0.3 T directed in the positive direction of the axisX . Find the magnitude and direction of the Lorentz force acting on a proton moving in the positive direction of the Y axis with a speedv = 5 10 6 m/s (proton charge e+ = 1.6 10 -19 C).
Summary of the lesson.
The action of a magnetic field on an electric current is used in the device of electrical measuring instruments. They are a class of devices used to measure quantities: current, voltage, frequency, capacitance, resistance, inductance ...
Electrical measuring instruments are used in industry, energy, scientific field, in everyday life.Announcement of grades
Homework.
§ 22; Notebook entries, No. 837, 838 (Rym.)
Reflection.
Lab 1
Topic:
Electrical measuring instruments and measurements.
Objective:
The study of electrical measuring instruments used in laboratory work performed at the stand.
Working process:
1.1 Studying the passport characteristics of pointer experimental devices.
Table 1 - Characteristics of electrical measuring instruments.
Name of devices Multimeter
Measuring mechanism system Electromagnetic
Measurement limit 100
Number of scale divisions 100
Scale division 1
Minimum measured value 1
Accuracy class 1
Permissible maximum absolute error 1%
Type of current DC and AC
Normal scale position Horizontal
Other Features Portable
1.2 Familiarize yourself with the front panel of the multimeter. When carrying out measurements in electrical circuits wide application received digital multimeters - combined digital measuring instruments that allow you to measure direct and alternating voltage, direct alternating current, resistance, check diodes and transistors. To carry out a specific measurement, it is necessary to set the proposed measurement limit of the measured value (current, voltage, resistance) with the switch, taking into account the type of current (direct or alternating). The presentation of the measurement result takes place on a digital readout device in the form of ordinary decimal numbers convenient for reading. Liquid crystal, gas-discharge and LED indicators are most widely used in digital reading devices of multimeters. On the front panel of such a device is a switch for functions and ranges. This switch is used both to select functions and the desired measurement range, and to turn off the device. To prolong the life of the instrument's power supply, the switch should be in the “OFF” position when the instrument is not in use.
The main technical characteristics of digital devices that must be considered when choosing include:
- measurement range (usually the device has several sub-ranges)
- resolution, which is often understood as the value of the measured quantity per unit of discreteness, that is, one quantum;
- input impedance characterizing the device's own consumption of energy from the source of measurement information;
- measurement error, often defined as +, - (% of read data + number of units of discharge).
The multimeter is often 9V battery powered, so before using the meter, check the battery by turning on the meter. If the battery is low, the battery icon will appear on the display. The multimeters used in the Elektrotekhnika stand are powered by a rectifier built into the module.
1.3 Prepare a multimeter to measure DC voltage.
Table 2 - DC voltage measurements.
Classes +5 V +12 V -12 V AN BN CN A-B B-C C-A
Nominal +4.5 +12.4 -12.1 218 219 220 376 377 377
Measured +5 +12 -12 220 220 220 380 380 380
Abs. burial 0.1 0.4 0.1 1 1 0 4 3 3
Relative burial (%) 2 1 0.8 0.9 0.4 0 1.1 1.1 0.8
1.4 Prepare a multimeter for measuring AC voltage. Measure the resistance values of the resistors indicated by the teacher. Record the results in table 3.
Table 3 - Resistance measurement.
Resistor R1 R2 R3 R4
Rated value of resistance, (Ohm) 10 20 30 40
Measured, (Ohm) 12 21 30 38
Absolute error 2 1 0 2
Relative error, (%) 0.001 4.7 0 5.2
Conclusion: we studied electrical measuring instruments used in laboratory work performed at the stand. We got an idea about the measurement limit, absolute and relative errors and other characteristics of pointer electrical measuring instruments, gaining skills in working with digital measuring instruments.
Test questions.
1. The principle of operation of a device of a magnetoelectric system is based on the phenomenon of the interaction of a magnetic field created in this device by a permanent magnet and a coil with a current. As a result of the interaction, the angle alpha of the turn of the pointer (coil rigidly connected to the pointer) is proportional to the magnitude of the current (J).
device electromagnetic system consists of a coil with current and a ferrimagnetic disk rigidly connected to the needle, which can enter the internal cavity of the coil. Thus, a magnetic field is created in the coil, the magnitude of the energy of which is proportional to the square of the current (J). The alpha angle of rotation of the disk in devices is proportional to the square of the effective current value (J)
2. The limit of measurement is the determination of a physical quantity empirically using measuring instruments.
3. The measurement limit of the device is divided by the number of strokes on the scale.
4. The absolute measurement error is equal to the difference between the measurement result and the true value of the measured quantity.
A \u003d Ah - A
The relative measurement error is the ratio absolute error measurements to true value measured value expressed in %.
bA \u003d A / A * 100%
5. Measuring instruments are divided into 8 accuracy classes: 0.05; 0.1; 0.5; 1.0; 1.5; 2.5; 4.0. The figure defining the accuracy class indicates the most acceptable value for the given device of the given basic error (in%)
6. An error in the measurement of any value with this device. The less, the closer values this value to the upper limit of the measurement of the device, therefore, for better use of the accuracy of the device, they should measure the value of the value of k / e corresponds to the second half of the scale of the device.
A = A-Ax
7. Digital electrical measuring instruments have high accuracy (error from 0.1 to 1%), faster response, wide measurement ranges, they are easily equipped with a digital computer, which transmit results without distortion over unlimited distances.
