Target: learn to use an ammeter to measure current in a circuit.
Task No. 1
1. Electric current is called:
A. Movement of electrons along a conductor
B. Orderly movement of electrons along a conductor
B. Orderly movement of electric charges along a conductor
2. What transformations occur in galvanic cells, Volta cells, batteries?
A. Internal energy is converted into electrical energy
B. Chemical energy is converted into electrical energy
B. Electrical energy is converted into mechanical energy
3. To obtain electric current in a conductor, you must:
A. Create electric charges in it
B. Separate the electric charges in it
B. Create an electric field in it
4. The direction of electric current in value is taken to be:
A. From the negative pole of the source to the positive pole
B. From the positive pole of the source to the negative
B. Along which electrons move in a conductor
5.What is electric current in metals and what is the effect of current on a conductor used in electric lamps?
A. Orderly movement of electric charges, chemical
B. Orderly movement of positively and negatively charged ions, magnetic
B. Orderly motion of electrons, thermal
6. The device for measuring current is called:
A.Barometer
B. Galvanometer
V. Ammeter
7. Formula for determining current strength:
8. Express 0.025 A in milliammeteres
Task No. 2
Complete the practice questions and lab assignments, continuing the sentences:
Task No. 3
Familiarize yourself with the laboratory ammeter and complete the table.
Remember! The ammeter cannot be connected directly to a current source, since in this case an excessively large current flows through it, which disables it.
Dynamic pause "Guess the words"
Task No. 4
According to the description of the laboratory work, draw circuits, assemble circuits, measure current and record ammeter readings.
Task No. 5
Draw a circuit diagram, measure the current and record the ammeter readings in a table.
Task No. 7
Write down your homework:
Assembling an electrical circuit and measuring the current in its various sections.
Goal of the work: verify from experience that the current strength in different series-connected sections of the circuit is the same.
This is your first electrical lab. In general, laboratory work on electricity is no more dangerous than changing the battery in a flashlight or electronic toy. But you will probably need to use your skills in working with electrical circuits and electrical appliances in the future, both in laboratory work in high school and at home. Therefore, we recommend that you listen carefully to what the teacher talks about safety precautions. It will be useful in life.
So in this lab we are going to measure the current in a circuit. We remember from the textbook that the current strength is equal to the ratio of the electric charge passing through the cross section of the conductor to the time of its passage.
If we use an analogy with a gutter through which water flows, then the current strength can be called the ratio of the volume of water passing through the cross-section of the gutter to the time of its passage. If water flows freely through the gutter, without accumulating anywhere, then the time it takes for one total volume of water to pass through the cross-section of the gutter is the same in any place. The same is true with electric current. The current strength in different sections of the circuit, where all devices are connected in series, is the same. What we have to verify from experience.
An example of the work being done.
1. What do the “+” and “-” signs near the device terminals mean?
These signs indicate the poles of the current source to which the device must be connected.
2. What is the maximum current strength it can measure?
3. What is the price of division of its scale?
What is the smallest current that can be measured by this device?
$C = 0.05 A$; $I_(min) = \frac(0.05)(2) = 0.025 A$.
1. Assemble the electrical circuit according to the figure. Check the correct assembly with a teacher! Complete the circuit.
2. Draw a circuit diagram and use a solid arrow to indicate the direction of current in the circuit, and a dotted arrow to indicate the direction of movement of charge carriers.
3. Reverse the direction of current in the circuit. Check the circuit with the teacher! Write how you did it and whether changing the direction of the current affected the strength of the current and the glow of the light bulb.
We swapped the wires on the current source and ammeter. The current strength has not changed.
4. Measure and enter into the table the values of the current flowing between the “+” terminal of the current source and the key (section 1); current flowing between the key and the light bulb (section 3); current strength I4 flowing between the light bulb and the “-” terminal of the current source (section 4). Draw conclusions about the current strength in different sections of the circuit.
$I_1 = 0.5 A$;
$I_2 = 0.5 A$;
$I_3 = 0.5 A$;
$I_4 = 1.25 A$.
5. Draw circuit diagrams for measuring currents $I_3$ and $I_4$.
Scheme 2 and Scheme 3
6. Replace the light bulb in the last circuit, first with a resistor on the socket, then with a resistor on the holders. Measure and enter into the table the values of the current strength in them $I_4"$ and $I_4"$.
7. Compare the current strengths of $I_4$, $I_3"$ and $I_4"$ and draw conclusions.
$I_1 = I_2 = I_3$;
$I_3< I_4$.
Turning on an ammeter at various points in the circuit does not change the current, but replacing a light bulb with a resistor changes the current.
1. Why is the current strength in different parts of the circuit the same?
Because current flows in different parts of the circuit in the same amount of time.
2. Will exclusion from the ammeter circuit affect the glow of the light bulb? Why?
No, it won't affect it. Because the ammeter has low resistance and consumes virtually no electricity.
Technological map of the lesson.
Item: physics
Class 9A ( hearing impaired children)
Teacher: Kishchenko Lidiya Mikhailovna
Subject: Current measurement. Laboratory work No. 3 “Assembling an electrical circuit and measuring the current strength in its various sections.”
Target: Formation of skills in assembling an electrical circuit; strengthening the skills of determining the division value, the measurement limit of an ammeter, its correct inclusion in a circuit and its use to measure current.
Tasks: 1) Find out how to measure current strength; 2) learn how to correctly connect an ammeter to an electrical circuit and measure current strength with it; 3) perform laboratory work on assembling an electrical circuit and measuring the current strength in its various sections.
Lesson type : Combined lesson.
Teaching methods: Visual, practical, inductive, laboratory work, frontal questioning.
Form of organization of educational activities of students: Group, individual.
Equipment: power supply, low-voltage lamp, key, ammeter, connecting wires; textbook, computer, projector.
Planned results:
Learn to assemble an electrical circuit, use an ammeter to determine the current strength in an electrical circuit, draw electrical circuit diagrams; be able to perform experiments, analyze and evaluate the results of the experiment.
| Lesson stage | Teacher activities | Student activities | |
| 1. Org. Moment | Greeting, checking the emotional mood of students (strong link) | Greetings from teachers | Regulatory: volitional self-regulation Personal: the action of meaning-making Communicative: planning educational cooperation with the teacher and peers |
| 2. Phonetic exercise. Duty sound: r | We speak correctly. Write: Ammeter Series | Speak the words Behind the screen: Electrical circuit | Regulatory: control, correction of correct pronunciation |
| 3. Creating motivation. Determining the topic of the lesson | Ask questions: Why do you need an ammeter? What will we do in class? What do you think is the topic of our lesson? After recording the topic, message of lesson objectives | Preparation for understanding the material and performing the work. Output on the topic of student activities. Write down the date and topic of the lesson in your notebooks. | Regulatory: understand, accept and maintain the learning task; Cognitive: searching and highlighting the necessary information, Communicative: expressing your thoughts and actions in speech, participating in a collective discussion of issues |
| 4.Intellectual warm-up Individual work | Let's review material that will help you and I remember what we learned in previous lessons. 1.What is the name of the device for measuring current? 2.How to distinguish an ammeter from other instruments? 3. Determine: 1. measurement limit 2. current value (presentation) | Answer questions | Personal: the ability to consciously construct speech utterances, educational skills to determine the central point Cognitive: establishing cause and effect relationships, building a logical chain of reasoning Communicative: the ability to express one’s thoughts sufficiently fully, mastery of monologue speech |
| 5.New topic. | Explain the rules for using an ammeter 1) Connected in series. 2) Switching is done using two terminals “+” and “-”. 3) The terminal with the “+” sign is connected to the “+” of the source, the “-” terminal to the “-”. 4) Protect the device from shock, shaking and dust. Working from the textbook page 89 fig. 61: what is shown in the figure? Preparation for LR: Look at the ammeters on your desks. The terminal with the (+) sign must be connected to the wire coming from the (+) pole of the source. Brief conclusions on the topic of the lesson: an ammeter is a device that is connected to a circuit... in series. The ammeter shows the value of...current strength. The operating principle of any ammeter is based on... action of electric current. (magnetic). Is it possible to connect an ammeter to a circuit with a current exceeding its maximum value? | Write it down in your notebook: the ammeter is connected in series in the circuit. Answer questions Participate in conversation Listening phrase: The ammeter is connected in series | Personal: educational and cognitive interest in new material; Regulatory: understand, accept and maintain a learning task, determine the sequence of actions, guided by the learned rules and instructions of the teacher; Cognitive: understand the general method of action to solve a learning task, apply it to solve specific problems Communicative: express your thoughts and actions in speech, participate in joint activities |
| 6.Checking homework. | Check notes in notebooks | They open the notebooks and show the LR | Personal: o student’s awareness of what has already been learned, awareness of the quality and level of assimilation |
| 7.Performing laboratory work No. 3 “Assembling an electrical circuit and measuring the current strength in its various sections.” | Open your lab notebooks. work, write down: number, progress of work. 1. sketch the electrical diagrams. circuits according to Fig. 155 a-v. Let's check at the board. 2. Electrical assembly circuits according to scheme No. 1. Arrange the circuit elements on the working field according to the diagram, assemble the circuit. Close the key and take ammeter readings. Write it down. 3. Conduct experiments according to schemes No. 2 and No. 3 and write down the measurement results in a notebook. 4. Compare I1, I2, I3 and write down the conclusion. | Work with the textbook and prepare a report. Draw diagrams in a notebook. Do practical work. Determine and write down in a notebook. Complete the task. They work in small groups. Perform a comparison and analyze the result. Write down the conclusion, hand over the notebooks for checking | Personal: cognitive interest in extracting information presented in symbolic form; Regulatory: understand, accept and maintain the learning task, determine the sequence of actions, guided by the learned rules and instructions of the teacher, exercise self-control and mutual control; Cognitive: analysis of objects to identify features, selection of bases and criteria for comparison Communicative: participate in a collective discussion of issues, provide the necessary assistance in cooperation, follow the rules of speech behavior |
| 8.Homework. P. 38, ex. 15 (1-3). |
Laboratory work No. 3 in physics, grade 8 (answers) - Assembling an electrical circuit and measuring the current in it
These signs indicate the poles of the current source to which the device must be connected.
C = 0.05 A; I min = (0.05)/2 = 0.025 A.
We swapped the wires on the current source and ammeter. The current strength has not changed.
Scheme 2 and Scheme 3
Turning on an ammeter at various points in the circuit does not change the current, but replacing a light bulb with a resistor changes the current.
Because current flows in different parts of the circuit in the same amount of time.
No, it won't affect it. Because the ammeter has low resistance and consumes virtually no electricity.
Because The current strength of the light bulb is 0.5 A, multiplying this value by the number of seconds we get 30 Coulombs. The general formula is q = I · t.
Move wire 3 from terminal C of the key to terminal B. Connect the freed terminal C of the key with an additional wire to the “+” terminal of the source. After turning on the circuit, explain how the position of the key affects the operation of the light bulb and ammeter.
Since the ammeter and lamp are not connected to anything, and the key is connected to the “+” terminal, the position of the key will not affect the operation of the lamp and ammeter.
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