Parallel connection voltage. Resistance series and parallel connection, conductor connections

All known types of conductors have certain properties, including electrical resistance. This quality has found its application in resistors, which are circuit elements with precisely set resistance. They allow you to adjust the current and voltage with high accuracy in circuits. All such resistances have their own individual qualities. For example, the power for parallel and series connection of resistors will be different. Therefore, in practice, various calculation methods are often used, thanks to which it is possible to obtain accurate results.

Properties and technical characteristics of resistors

As already noted, resistors in electrical circuits and circuits perform a regulatory function. For this purpose, Ohm's law is used, expressed by the formula: I \u003d U / R. Thus, with a decrease in resistance, a noticeable increase in current occurs. Conversely, the higher the resistance, the lower the current. Due to this property, resistors are widely used in electrical engineering. On this basis, current dividers are created, which are used in the designs of electrical devices.

In addition to the current regulation function, resistors are used in voltage divider circuits. In this case, Ohm's law will look a little different: U \u003d I x R. This means that with increasing resistance, an increase in voltage occurs. This principle is based on the entire operation of devices designed for voltage division. For current dividers, a parallel connection of resistors is used, and for a series connection.

On the diagrams, resistors are displayed as a rectangle, 10x4 mm in size. The symbol R is used for designation, which can be supplemented by the power value of this element. For power over 2 W, the designation is done using Roman numerals. The corresponding inscription is applied on the circuit near the resistor icon. Power is also included in the composition applied to the body of the element. Resistance units are ohm (1 ohm), kiloohm (1000 ohm) and megaohm (1000000 ohm). The range of resistors ranges from fractions of an ohm to several hundred megaohms. Modern technologies make it possible to manufacture these elements with fairly accurate resistance values.

An important parameter of the resistor is the resistance deviation. Its measurement is carried out as a percentage of the nominal value. The standard deviation series is the values ​​in the form: + 20, + 10, + 5, + 2, + 1% and so on up to the value + 0,001%.

Of great importance is the power of the resistor. During operation, an electric current passes through each of them, causing heating. If the allowable value of power dissipation exceeds the norm, this will lead to the failure of the resistor. It should be borne in mind that during the heating process, a change in the resistance of the element occurs. Therefore, if the devices operate in wide temperature ranges, a special value is used, called the temperature coefficient of resistance.

To connect resistors in circuits, three different connection methods are used - parallel, series and mixed. Each method has individual qualities, which allows you to use these elements for a variety of purposes.

Power in serial connection

When resistors are connected in series, current passes through each resistor in turn. The value of the current at any point in the circuit will be the same. This fact is determined using Ohm's law. If you add up all the resistances shown in the diagram, you get the following result: R \u003d 200 + 100 + 51 + 39 \u003d 390 Ohms.

Given the voltage in the circuit, equal to 100 V, the current strength will be I \u003d U / R \u003d 100/390 \u003d 0.256 A. Based on the data obtained, you can calculate the power of the resistors in series connection using the following formula: P \u003d I 2 x R \u003d 0.256 2 x 390 = 25.55 watts.

• P 1 \u003d I 2 x R 1 \u003d 0.256 2 x 200 \u003d 13.11 W;
• P 2 \u003d I 2 x R 2 \u003d 0.256 2 x 100 \u003d 6.55 W;
• P 3 \u003d I 2 x R 3 \u003d 0.256 2 x 51 \u003d 3.34 W;
• P 4 \u003d I 2 x R 4 \u003d 0.256 2 x 39 \u003d 2.55 W.

If we add up the received power, then the total P will be: P \u003d 13.11 + 6.55 + 3.34 + 2.55 \u003d 25.55 watts.

Power in parallel connection

When connected in parallel, all the beginnings of the resistors are connected to one node of the circuit, and the ends to another. In this case, the current branching occurs, and it begins to flow through each element. According to Ohm's law, the current will be inversely proportional to all connected resistances, and the voltage across all resistors will be the same.

Before calculating the current strength, it is necessary to calculate the total conductivity of all resistors using the following formula:

• 1/R = 1/R 1 +1/R 2 +1/R 3 +1/R 4 = 1/200+1/100+1/51+1/39 = 0.005+0.01+0.0196+ 0.0256 = 0.06024 1/ohm.
• Since resistance is a quantity inversely proportional to conductivity, its value will be: R \u003d 1 / 0.06024 \u003d 16.6 ohms.
• Using a voltage value of 100 V, the current strength is calculated according to Ohm's law: I \u003d U / R \u003d 100 x 0.06024 \u003d 6.024 A.
• Knowing the current strength, the power of the resistors connected in parallel is determined as follows: P \u003d I 2 x R \u003d 6.024 2 x 16.6 \u003d 602.3 W.
• The calculation of the current strength for each resistor is carried out according to the formulas: I 1 \u003d U / R 1 \u003d 100/200 \u003d 0.5A; I 2 \u003d U / R 2 \u003d 100/100 \u003d 1A; I 3 \u003d U / R 3 \u003d 100/51 \u003d 1.96A; I 4 \u003d U / R 4 \u003d 100/39 \u003d 2.56A. On the example of these resistances, a pattern can be traced that with a decrease in resistance, the current strength increases.

There is another formula that allows you to calculate the power when resistors are connected in parallel: P 1 \u003d U 2 / R 1 \u003d 100 2 / 200 \u003d 50 W; P 2 \u003d U 2 / R 2 \u003d 100 2 / 100 \u003d 100 W; P 3 \u003d U 2 / R 3 \u003d 100 2 / 51 \u003d 195.9 W; P 4 \u003d U 2 / R 4 \u003d 100 2 / 39 \u003d 256.4 W. Adding the power of individual resistors, you get their total power: P = P 1 + P 2 + P 3 + P 4 = 50 + 100 + 195.9 + 256.4 = 602.3 watts.

Thus, the power for series and parallel connection of resistors is determined in different ways, with the help of which you can get the most accurate results.

Usually everyone finds it difficult to answer. But this riddle, as applied to electricity, is solved quite definitely.

Electricity starts with Ohm's law.

And if we consider the dilemma in the context of parallel or series connections - considering one connection as a chicken and the other as an egg, then there is no doubt at all.

Because Ohm's law is the very original electrical circuit. And it can only be consistent.

Yes, they came up with a galvanic cell and did not know what to do with it, so they immediately came up with another light bulb. And here's what came out of it. Here, a voltage of 1.5 V immediately flowed as a current, in order to strictly comply with Ohm's law, through a light bulb to the back of the same battery. And inside the battery itself, under the influence of the sorceress-chemistry, the charges again ended up at the initial point of their campaign. And therefore, where the voltage was 1.5 volts, it remains so. That is, the voltage is constantly the same, and the charges are constantly moving and sequentially pass the light bulb and the galvanic cell.

And this is usually drawn on the diagram like this:

According to Ohm's law I=U/R

Then the resistance of the light bulb (with the current and voltage that I wrote) will be

R= 1/U, whereR = 1 Ohm

And the power will be released P = I * U , i.e. P=2.25 Vm

In a series circuit, especially in such a simple and undoubted example, it is clear that the current that runs through it from beginning to end is the same all the time. And if we now take two bulbs and make it so that the current runs first through one and then through the other, then the same thing will happen again - the current will be the same in that bulb and in the other again. Although different in size. The current is now experiencing the resistance of two light bulbs, but each of them has the same resistance as it was, because it is determined solely by the physical properties of the light bulb itself. The new current is calculated again according to Ohm's law.

It will turn out to be equal to I \u003d U / R + R, that is, 0.75A, exactly half of the current that was at first.

In this case, the current has to overcome two resistances, it becomes smaller. As can be seen from the glow of the bulbs - they are now burning half-heartedly. And the total resistance of a chain of two light bulbs will be equal to the sum of their resistances. Knowing arithmetic, in a separate case, you can also use the multiplication action: if N identical bulbs are connected in series, then their total resistance will be equal to N times R, where R is the resistance of one bulb. The logic is impeccable.

And we will continue our experiments. Now we will do something similar to what we did with the bulbs, but only on the left side of the circuit: we will add another galvanic cell, exactly like the first one. As you can see, now we have doubled the total voltage, and the current has again become 1.5 A, which is what the bulbs signal, lighting up again at full strength.

We conclude:

• When an electrical circuit is connected in series, the resistances and voltages of its elements are summed up, and the current on all elements remains unchanged.

It is easy to verify that this statement is true for both active components (galvanic cells) and passive ones (bulbs, resistors).

That is, this means that the voltage measured across one resistor (it is called the voltage drop) can be safely added to the voltage measured across the other resistor, and the total will be the same 3 V. And on each of the resistances it will be equal to half - then there is 1.5 V. And rightfully so. Two galvanic cells generate their voltages, and two light bulbs consume them. Because in a voltage source, the energy of chemical processes is converted into electricity, which has taken the form of voltage, and in light bulbs the same energy is converted from electrical into heat and light.

Let's go back to the first circuit, connect another light bulb in it, but in a different way.

Now the voltage at the points connecting the two branches is the same as on the galvanic cell - 1.5 V. But since the resistance of both bulbs is also the same as it was, then the current through each of them will go 1.5 A - current "full glow".

The galvanic cell now feeds them with current at the same time, therefore, both of these currents flow from it at once. That is, the total current from the voltage source will be 1.5 A + 1.5 A = 3.0 A.

What is the difference between this circuit and the circuit when the same light bulbs were connected in series? Only in the glow of light bulbs, that is, only in current.

Then the current was 0.75 A, and now it has become 3 A at once.

It turns out, if compared with the original circuit, when the bulbs were connected in series (scheme 2), the resistance current turned out to be greater (why it decreased, and the bulbs lost their luminosity), and the parallel connection has LESS resistance, although the resistance of the bulbs remained unchanged. What's the matter here?

But the fact is that we forget one interesting truth that every stick has two ends.

When we say that a resistor resists current, we kind of forget that it still conducts current. And now, when the light bulbs are connected in parallel, the total property for them to conduct current has increased, and not to resist it. Well, and, accordingly, a certain value G, by analogy with the resistance R and should be called conductivity. And it should be summed up in a parallel connection of conductors.

Well, here she is

Ohm's law would then look like

I = U* G&

And in the case of a parallel connection, the current I will be equal to U * (G + G) \u003d 2 * U * G, which is exactly what we are observing.

Replacing circuit elements with a common equivalent element

Engineers often need to know currents and voltages in all parts of circuits. And real electrical circuits are quite complex and branched and may contain many elements that actively consume electricity and are connected to each other in completely different combinations. This is called the calculation of electrical circuits. It is done when designing the energy supply of houses, apartments, organizations. At the same time, it is very important what currents and voltages will act in the electrical circuit, if only in order to select the wire sections that suit them, the loads on the entire network or its parts, and so on. And I think everyone understands how complex electronic circuits containing thousands, or even millions of elements, are.

The very first thing that suggests itself is to use the knowledge of how voltage currents behave in such simple network connections as serial and parallel. They do this: instead of the serial connection of two or more active consumer devices (like our light bulbs) found on the network, draw one, but so that its resistance is the same as that of both. Then the pattern of currents and voltages in the rest of the circuit will not change. Similarly, with a parallel connection: instead of them, draw an element whose CONDUCTIVITY would be the same as both.

Now, if the circuit is redrawn, replacing the serial and parallel connections with one element, we will get a circuit called the “equivalent substitution circuit”.

This procedure can be continued until we have the simplest one left - with which we illustrated Ohm's law at the very beginning. Only instead of a light bulb there will be one resistance, which is called the equivalent load resistance.

This is the first task. It gives us the opportunity, using Ohm's law, to calculate the total current in the entire network, or the total load current.

This is the complete calculation of the electrical network.

Examples

Let the circuit contain 9 active resistances. It could be light bulbs or something else.

A voltage of 60 V is applied to its input terminals.

The resistance values ​​for all elements are as follows:

Find all unknown currents and voltages.

It is necessary to follow the path of searching for parallel and serial sections of the network, calculate their equivalent resistances and gradually simplify the circuit. We see that R 3 , R 9 and R 6 are connected in series. Then their equivalent resistance R e 3, 6, 9 will be equal to their sum R e 3, 6, 9 \u003d 1 + 4 + 1 Ohm \u003d 6 Ohm.

Now we replace the parallel piece from the resistances R 8 and R e 3, 6, 9, getting R e 8, 3, 6, 9. Only when the conductors are connected in parallel, the conductivity will have to be added.

Conductivity is measured in units called Siemens, reciprocal of ohms.

If you turn the fraction, we get the resistance R e 8, 3, 6, 9 \u003d 2 Ohm

In exactly the same way as in the first case, we combine the resistances R 2, R e 8, 3, 6, 9 and R 5, connected in series, getting R e 2, 8, 3, 6, 9, 5 \u003d 1 + 2 + 1 = 4 ohms.

There are two steps left: get a resistance equivalent to two resistors in parallel connection of conductors R 7 and R e 2, 8, 3, 6, 9, 5.

It is equal to R e 7, 2, 8, 3, 6, 9, 5 \u003d 1 / (1/4 + 1/4) \u003d 1 / (2/4) \u003d 4/2 \u003d 2 ohms

At the last step, we sum up all the series-connected resistances R 1, R e 7, 2, 8, 3, 6, 9, 5 and R 4 and get a resistance equivalent to the resistance of the entire circuit R e and equal to the sum of these three resistances

R e \u003d R 1 + R e 7, 2, 8, 3, 6, 9, 5 + R4 \u003d 1 + 2 + 1 \u003d 4 Ohm

Well, let's remember in whose honor the resistance unit written by us in the last of these formulas was named, and we calculate, according to his law, the total current in the entire circuit I

Now, moving in the opposite direction, towards the increasing complexity of the network, it is possible to obtain, according to Ohm's law, currents and voltages in all chains of our fairly simple circuit.

This is usually how the power supply schemes of apartments are calculated, which consist of parallel and serial sections. Which, as a rule, is not suitable in electronics, because there are many things arranged differently, and everything is much more intricate. And here, for example, such a circuit, when you don’t understand whether this is a parallel connection of conductors or in series, is calculated according to Kirchhoff’s laws.

The current in the electrical circuit passes through the conductors from the voltage source to the load, that is, to lamps, appliances. In most cases, copper wires are used as conductors. A circuit can have several elements with different resistances. In the instrument circuit, conductors can be connected in parallel or in series, and there can also be mixed types.

A circuit element with resistance is called a resistor, the voltage of this element is the potential difference between the ends of the resistor. Parallel and series electrical connection of conductors is characterized by a single principle of operation, according to which the current flows from plus to minus, respectively, the potential decreases. On wiring diagrams, the wiring resistance is taken as 0, since it is negligible.

Parallel connection assumes that the elements of the circuit are connected to the source in parallel and are switched on at the same time. Serial connection means that the resistance conductors are connected in strict sequence one after the other.

When calculating, the idealization method is used, which greatly simplifies understanding. In fact, in electrical circuits, the potential gradually decreases in the process of moving through the wiring and elements that are included in a parallel or series connection.

Serial connection of conductors

The serial connection scheme implies that they are switched on in a certain sequence, one after the other. Moreover, the current strength in all of them is equal. These elements create a total voltage on the site. Charges do not accumulate in the nodes of the electrical circuit, since otherwise a change in voltage and current would be observed. With a constant voltage, the current is determined by the value of the resistance of the circuit, therefore, in a series circuit, the resistance changes if one load changes.

The disadvantage of such a scheme is the fact that in the event of failure of one element, the rest also lose the ability to function, since the circuit is broken. An example is a garland that does not work if one light bulb burns out. This is a key difference from a parallel connection, where the elements can function separately.

The series circuit assumes that, due to the single-level connection of conductors, their resistance is equal at any point in the network. The total resistance is equal to the sum of the voltage reduction of the individual elements of the network.

With this type of connection, the beginning of one conductor is connected to the end of another. The key feature of the connection is that all conductors are on the same wire without branches, and one electric current flows through each of them. However, the total voltage is equal to the sum of the voltages on each. You can also consider the connection from a different point of view - all conductors are replaced by one equivalent resistor, and the current on it is the same as the total current that passes through all resistors. The equivalent total voltage is the sum of the voltage values ​​across each resistor. This is the potential difference across the resistor.

Using a serial connection is useful when you want to specifically turn on and off a specific device. For example, an electric bell can only ring when there is a connection to a voltage source and a button. The first rule says that if there is no current on at least one of the elements of the circuit, then it will not be on the rest. Accordingly, if there is current in one conductor, it is in the others. Another example would be a battery-powered flashlight, which only shines when there is a battery, a working bulb, and a pressed button.

In some cases, a serial scheme is not practical. In an apartment where the lighting system consists of many lamps, sconces, chandeliers, you should not organize a scheme of this type, since there is no need to turn the lights on and off in all rooms at the same time. For this purpose, it is better to use a parallel connection in order to be able to turn on the light in individual rooms.

Parallel connection of conductors

In a parallel circuit, conductors are a set of resistors, one end of which is assembled into one node, and the other ends into a second node. It is assumed that the voltage in the parallel type of connection is the same in all parts of the circuit. Parallel sections of the electrical circuit are called branches and pass between two connecting nodes, they have the same voltage. This voltage is equal to the value on each conductor. The sum of the reciprocal resistances of the branches is also the inverse of the resistance of a separate section of the parallel circuit circuit.

With parallel and series connections, the system for calculating the resistances of individual conductors is different. In the case of a parallel circuit, the current flows through the branches, which increases the conductivity of the circuit and reduces the total resistance. When several resistors with similar values ​​\u200b\u200bare connected in parallel, the total resistance of such an electrical circuit will be less than one resistor a number of times equal to the number.

Each branch has one resistor, and the electric current, when it reaches the branching point, is divided and diverges to each resistor, its final value is equal to the sum of the currents on all resistances. All resistors are replaced with one equivalent resistor. Applying Ohm's law, the value of the resistance becomes clear - in a parallel circuit, the values ​​​​reciprocal of the resistances on the resistors are summed up.

With this circuit, the current value is inversely proportional to the resistance value. The currents in the resistors are not interconnected, so if one of them is turned off, this will in no way affect the others. For this reason, such a scheme is used in many devices.

Considering the possibilities of using a parallel circuit in everyday life, it is advisable to note the lighting system of the apartment. All lamps and chandeliers must be connected in parallel, in which case turning one of them on and off does not affect the operation of the other lamps. Thus, by adding a switch for each light bulb to a branch of the circuit, you can turn the corresponding light on and off as needed. All other lamps work independently.

All electrical appliances are connected in parallel to a 220 V power grid, then they are connected to. That is, all devices are connected regardless of the connection of other devices.

Laws of series and parallel connection of conductors

For a detailed understanding in practice of both types of compounds, we present formulas that explain the laws of these types of compounds. The power calculation for parallel and series connection is different.

In a series circuit, there is the same current strength in all conductors:

According to Ohm's law, these types of conductor connections are explained differently in different cases. So, in the case of a series circuit, the voltages are equal to each other:

U1 = IR1, U2 = IR2.

In addition, the total voltage is equal to the sum of the voltages of the individual conductors:

U = U1 + U2 = I(R1 + R2) = IR.

The total resistance of the electrical circuit is calculated as the sum of the active resistances of all conductors, regardless of their number.

In the case of a parallel circuit, the total voltage of the circuit is similar to the voltage of the individual elements:

And the total strength of the electric current is calculated as the sum of the currents that are available in all conductors located in parallel:

To ensure the maximum efficiency of electrical networks, it is necessary to understand the essence of both types of connections and apply them appropriately, using the laws and calculating the rationality of practical implementation.

Mixed connection of conductors

Series and parallel resistance connections can be combined in one electrical circuit if necessary. For example, it is allowed to connect parallel resistors in series or in a group of them; this type is considered combined or mixed.

In such a case, the total resistance is calculated by taking the sum of the values ​​for the parallel connection in the system and for the series connection. First you need to calculate the equivalent resistances of the resistors in the series circuit, and then the elements of the parallel circuit. A serial connection is considered a priority, and circuits of this combined type are often used in household appliances and appliances.

So, considering the types of connections of conductors in electrical circuits and based on the laws of their functioning, one can fully understand the essence of the organization of circuits of most household electrical appliances. With parallel and series connections, the calculation of resistance and current strength indicators is different. Knowing the principles of calculation and formulas, you can competently use each type of circuit organization to connect elements in the best way and with maximum efficiency.

Content:

As you know, the connection of any circuit element, regardless of its purpose, can be of two types - parallel connection and serial connection. Mixed, that is, series-parallel connection is also possible. It all depends on the purpose of the component and the function it performs. So, the resistors did not escape these rules. The series and parallel resistance of resistors is essentially the same as the parallel and series connection of light sources. In a parallel circuit, the connection diagram implies an input to all resistors from one point, and an output from another. Let's try to figure out how a serial connection is made, and how a parallel connection is made. And most importantly, what is the difference between such connections and in which cases a serial connection is necessary, and in which parallel connection. Also of interest is the calculation of such parameters as the total voltage and total resistance of the circuit in cases of series or parallel connection. Let's start with definitions and rules.

Connection methods and their features

The types of connection of consumers or elements play a very important role, because the characteristics of the entire circuit, the parameters of individual circuits, and the like depend on this. To begin with, let's try to deal with the serial connection of elements to the circuit.

serial connection

A serial connection is a connection where resistors (as well as other consumers or circuit elements) are connected one after another, while the output of the previous one is connected to the input of the next one. This type of switching elements gives an indicator equal to the sum of the resistances of these circuit elements. That is, if r1 \u003d 4 ohms, and r2 \u003d 6 ohms, then when they are connected in a series circuit, the total resistance will be 10 ohms. If we add another 5 ohm resistor in series, adding these numbers will give 15 ohms - this will be the total resistance of the series circuit. That is, the total values ​​\u200b\u200bare equal to the sum of all resistances. When it is calculated for elements that are connected in series, no questions arise - everything is simple and clear. That is why you should not even dwell more seriously on this one.

Completely according to other formulas and rules, the total resistance of resistors is calculated when connected in parallel, so it makes sense to dwell on it in more detail.

Parallel connection

Parallel is a connection in which all the inputs of the resistors are combined at one point, and all the outputs at the second. The main thing here is to understand that the total resistance with such a connection will always be lower than the same parameter of the resistor with the smallest one.

It makes sense to analyze this feature with an example, then it will be much easier to understand. There are two 16 ohm resistors, but only 8 ohms are needed to properly wire the circuit. In this case, when both of them are involved, when they are connected in parallel to the circuit, the necessary 8 ohms will be obtained. Let's try to understand by what formula calculations are possible. This parameter can be calculated as follows: 1/Rtotal = 1/R1+1/R2, and when adding elements, the sum can continue indefinitely.

Let's try another example. 2 resistors are connected in parallel, with a resistance of 4 and 10 ohms. Then the total will be equal to 1/4 + 1/10, which will be equal to 1: (0.25 + 0.1) = 1: 0.35 = 2.85 ohms. As you can see, although the resistors had significant resistance, when connected in parallel, their total indicator became much lower.

You can also calculate the total resistance of four resistors connected in parallel, with a nominal value of 4, 5, 2 and 10 ohms. Calculations, according to the formula, will be as follows: 1 / Rtotal \u003d 1/4 + 1/5 + 1/2 + 1/10, which will be equal to 1: (0.25 + 0.2 + 0.5 + 0.1) \u003d 1 / 1.5 \u003d 0.7 Ohm.

As for the current flowing through resistors connected in parallel, here it is necessary to refer to Kirchhoff's law, which states that "the current in parallel connection leaving the circuit is equal to the current entering the circuit." And because here the laws of physics decide everything for us. In this case, the total current indicators are divided into values ​​that are inversely proportional to the resistance of the branch. To put it simply, the higher the resistance value, the smaller the currents will pass through this resistor, but in general, the input current will still be at the output. When connected in parallel, the voltage at the output also remains the same as at the input. The parallel connection diagram is shown below.

Series-parallel connection

Series-parallel connection is when the series connection circuit contains parallel resistances. In this case, the total series resistance will be equal to the sum of the individual total parallel ones. The calculation method is the same in the respective cases.

Summarize

Summarizing all of the above, the following conclusions can be drawn:

1. When resistors are connected in series, no special formulas are required to calculate the total resistance. It is only necessary to add up all the indicators of the resistors - the sum will be the total resistance.
2. When resistors are connected in parallel, the total resistance is calculated by the formula 1/Rtotal = 1/R1+1/R2…+Rn.
3. The equivalent resistance in parallel connection is always less than the minimum similar indicator of one of the resistors included in the circuit.
4. The current, as well as the voltage in a parallel connection, remains unchanged, that is, the voltage in a series connection is the same both at the input and at the output.
5. A series-parallel connection in calculations obeys the same laws.

In any case, whatever the connection, it is necessary to clearly calculate all the indicators of the elements, because the parameters play a very important role in the installation of circuits. And if you make a mistake in them, then either the circuit will not work, or its elements will simply burn out from overload. In fact, this rule applies to any circuit, even in wiring. After all, the wire according to the cross section is also selected based on power and voltage. And if you put a light bulb with a nominal value of 110 volts into a circuit with a voltage of 220, it is easy to understand that it will burn out instantly. It is the same with the elements of radio electronics. And therefore - attentiveness and scrupulousness in calculations - the key to the correct operation of the circuit.

One of the pillars on which many concepts in electronics are based is the concept of series and parallel connection of conductors. It is simply necessary to know the main differences between these types of connection. Without this, it is impossible to understand and read a single diagram.

Basic principles

Electric current moves along the conductor from the source to the consumer (load). Most often, a copper cable is selected as a conductor. This is due to the requirement that is placed on the conductor: it must easily release electrons.

Regardless of the connection method, the electric current moves from plus to minus. It is in this direction that the potential decreases. It is worth remembering that the wire through which the current flows also has resistance. But its value is very small. That is why they are neglected. Conductor resistance is assumed to be zero. In the event that the conductor has resistance, it is customary to call it a resistor.

Parallel connection

In this case, the elements included in the chain are interconnected by two nodes. They have no connections with other nodes. Sections of the chain with such a connection are called branches. The parallel connection diagram is shown in the figure below.

Speaking in a more understandable language, then in this case all the conductors are connected at one end in one node, and the other - in the second. This leads to the fact that the electric current is divided into all elements. This increases the conductivity of the entire circuit.

When connecting conductors to a circuit in this way, the voltage of each of them will be the same. But the current strength of the entire circuit will be determined as the sum of the currents flowing through all the elements. Taking into account Ohm's law, by simple mathematical calculations, an interesting pattern is obtained: the reciprocal of the total resistance of the entire circuit is defined as the sum of the reciprocals of the resistances of each individual element. Only elements connected in parallel are taken into account.

Serial connection

In this case, all elements of the chain are connected in such a way that they do not form a single node. This connection method has one significant drawback. It lies in the fact that if one of the conductors fails, all subsequent elements will not be able to work. A striking example of such a situation is an ordinary garland. If one of the bulbs in it burns out, then the whole garland stops working.

The series connection of elements is different in that the current strength in all conductors is equal. As for the voltage of the circuit, it is equal to the sum of the voltages of the individual elements.

In this circuit, the conductors are included in the circuit in turn. And this means that the resistance of the entire circuit will be the sum of the individual resistances characteristic of each element. That is, the total resistance of the circuit is equal to the sum of the resistances of all conductors. The same dependence can also be derived mathematically using Ohm's law.

mixed schemes

There are situations when on the same circuit you can see both serial and parallel connection of elements. In this case, we speak of a mixed connection. The calculation of such schemes is carried out separately for each of the group of conductors.

So, to determine the total resistance, it is necessary to add the resistance of the elements connected in parallel and the resistance of the elements connected in series. In this case, the serial connection is dominant. That is, it is calculated in the first place. And only after that, the resistance of elements with parallel connection is determined.

Connecting LEDs

Knowing the basics of the two types of connecting elements in a circuit, you can understand the principle of creating circuits for various electrical appliances. Consider an example. largely depends on the voltage of the current source.

With a low mains voltage (up to 5 V), the LEDs are connected in series. In this case, a pass-through capacitor and linear resistors will help to reduce the level of electromagnetic interference. The conductivity of the LEDs is increased through the use of system modulators.

With a mains voltage of 12 V, both serial and parallel mains connections can be used. In the case of serial connection, switching power supplies are used. If a circuit of three LEDs is assembled, then an amplifier can be dispensed with. But if the circuit will include more elements, then an amplifier is needed.

In the second case, that is, with a parallel connection, it is necessary to use two open resistors and an amplifier (with a bandwidth above 3 A). Moreover, the first resistor is installed in front of the amplifier, and the second - after.

With a high mains voltage (220 V), they resort to a serial connection. In this case, operational amplifiers and step-down power supplies are additionally used.