# Circuit resistance calculation

Sections: Physics

Objectives:

Educational: systematize and consolidate students' knowledge of various connections of conductors, develop skills in applying the laws of serial and parallel connections for calculating electrical circuits, combine knowledge gained in physics and mathematics.
• Developing: develop students' thinking, enhance cognitive activity through solving problems on the calculation of electrical circuits, develop the ability to calculate the parameters of electrical circuits and improve the skills learned in the lesson.
• Educational: the formation of interest in the studied subject, to continue the formation of communicative skills.

Lesson Type: lesson testing and consolidating new knowledge in physics and mathematics.

Lesson Method: practical

Equipment:

• Gromov S.V. Textbook “Physics-9”,
• lesson plan
• methodology for calculating a portion of a direct current electric circuit

Today in the lesson, we must apply the knowledge we obtained earlier about the laws of serial and parallel connections to calculate the area of ​​the electrical circuit, and also determine the degree of assimilation of the material studied using the cards - tasks.

Before starting to consider electrical circuits, remember what we already know and answer the questions:

1) What types of connections are and how are they shown on the electrical diagrams?
2) What are the laws of serial connection?
3) What are the laws of parallel connection?
4) What is the distinguishing feature of parallel connection?

Consider the calculation of the electric circuit on the example of the following tasks:

1. Calculate the total electrical resistance of the circuit? 1) The most remote elements from the source are the resistors R2 and R3.

2) Combine these two resistors in the first section and calculate their total resistance. R resistors2 and R3 connected in parallel, because they form two nodes in the connection, therefore:

Ohm

3) We depict the resulting resistors R2 and R3 electric circuit:

4) We group the circuit with two resistors as a result of combining in the second section and calculate their total resistance. Since the resistors R1 and Rvol.1 connected in series, which means:

Answer: the total resistance of the resistors in the section of the electric circuit is 6 ohms.

2. Calculate the total electrical resistance of the circuit? 1) R resistors1 and R2 interconnected in series:

We will depict the obtained electrical section of the circuit: 2) R resistors3 and R4 interconnected in series:

We will depict the obtained electrical section of the circuit: 3) Group the circuit with two resistors obtained as a result of combining in the third section and calculate their total resistance. Since the resistors Rvol.1 and Rvol.2 connected in parallel, which means:

Ohm

Answer: The total resistance of the resistors in the 2.1-ohm section of the circuit.

3. Perform the tasks yourself on the cards (differentiated), using the reminder for calculating the area of ​​the DC electric circuit:

a) Calculate the total electrical resistance of the circuit? b) Calculate the total electrical resistance of the circuit? c) Calculate the total electrical resistance of the circuit? Today in the lesson we examined various schemes of sections of electrical circuits, learned how to calculate circuits using the laws of serial and parallel connections, and also consolidated the knowledge with the help of cards - tasks.