I don t understand the problem of series resistance and parallel resistance, please ask experts to h

Series connection, that is, only one circuit can go from the positive to the negative, and the parallel circuit, that is, there are multiple ways that can go from the positive to the negative, which produces many invariants, the current of the series circuit is constant, and the voltage of the parallel circuit is unchanged Related formulas: i=u r (ohm rate) p=w t (electrical power definition formula, universally applicable) p=ui (electrical power calculation formula, universally applicable) p=i square r (suitable for calculating the electric power formula of some electrical appliances in series circuits, and also a formula for pure resistance circuits) p=u square r (suitable for calculating the total power of series circuits, that is, the voltage is unchanged, as well as the total power of parallel circuits and the power formula of electrical appliances in part of the branches, the applicable frequency is the highest, pure resistance circuit formula), when calculating, it is necessary to see the invariants clearly, and extract some of the amounts it gives according to the needs of the problem, and select the appropriate formula, as well as electrical work, that is, multiply the time by the previous formulas, The first formula is deformed, as for electric heating, it is necessary to remember a universally applicable formula, q=i square rt, which is often used, and the others are also multiplied by the last time, which are pure resistance circuit electric heating formulas, probably that's it, it's not difficult in practice, and you will be familiar with it when you practice doing more.

You're going to tell me why I don't understand... If you use a string, you will use a string, and if you merge it, you will use it, and if you don't understand something.

In a series circuit, r=r1+r2

In the parallel circuit, r=r1r2 (r1+r2), i.e., 1 r1=1 r1+1 r2

The relationship between the resistors in the series-parallel circuit is as follows:

The total resistance of the series circuit is equal to the sum of the resistances of the series conductors, i.e., r string r1+r2+-+rn.

The reciprocal of the total resistance of the parallel circuit is equal to the reciprocal sum of the parallel resistors, i.e., 1 r parallel 1 r1 + 1 r2 + --1 rn.

The relationship between resistance and power of a series circuit.

In a series circuit, by p=ui=i r, when i is the same, the larger r is, the greater p is. That is, in a series circuit, the greater the resistance, the greater the actual electrical power. In a parallel circuit, p=ui=u r, when u is the same, the larger r is, the smaller p is.

So in a parallel circuit, the greater the resistance, the smaller the actual electrical power.

Electrical power is a physical quantity that indicates how fast or slow an electric current is done, and the magnitude of the power of an electrical appliance is numerically equal to the amount of electrical energy it consumes in 1 second. If the electrical energy W (Si unit J) is consumed for such a long time as t (Si unit J), then the electrical power of this appliance is p=w t. The electrical power is also equal to the product of the voltage across the conductor and the current passing through the conductor.

Tandem:It is one of the basic ways to connect circuit components. Circuit components (such as resistors, capacitors, inductors, electrical appliances, etc.) are connected one by one.

Parallel:It is a connection mode between components, which is characterized by connecting two components and devices of the same or different kinds, and the tail is also connected at the same time.

The difference between the two:

Resistance series should refer to series circuits, which refers to the circuit connection method in which the resistors are connected one by one like a string of beads.

The parallel connection of resistors should refer to parallel circuits, that is, in the circuit diagram, the connection forms of each resistor are parallel to each other.

Features of resistor series:

1) The currents flowing through each resistor are equal.

2) The total voltage on the series resistors is equal to the sum of the voltages on each resistor.

3) The total resistance of the series resistors is equal to the sum of the resistors.

Characteristics of resistor paralleling:

1) The voltage on each shunt resistor is the same.

2) The total current of the parallel resistors is equal to the sum of the currents flowing through each resistor.

3) The equivalent resistance of the parallel resistor is equal to the reciprocal of the sum of the reciprocals of each parallel resistor.

Resistors are connected in series, meaning that the current flowing through each resistor is the same current. Resistors are parallel, which means that the voltage of each resistor is the same voltage.

The so-called resistor series means that the current flowing through each resistor is the same current. In other words, there are no (tributary) branch currents between the series resistors. The total resistance is directly equal to the direct addition of each sub-resistance, and the resistance value of the resistance is proportional to its length, so the resistance is connected in series, just like increasing the length, the more strings, the longer the length, the greater the resistance.

In addition, according to Ohm's law, the voltage division formula for two series resistors can be derived.

The so-called resistor parallel connection means that the voltage of each resistor is the same voltage. In other words, all parallel resistors share two junctions, the first is connected and the tail is connected, and it is clear that the equivalent resistance is less than that of any one of the resistors in parallel. This is because the reciprocal of the total resistance is equal to the sum of the reciprocals of the individual parallel resistors, that is, the reciprocal of the total resistance must be greater than the reciprocal of any parallel resistor.

In the same way, since the reciprocal of the total resistance is greater than the reciprocal of any parallel resistor, the total resistance as the denominator must be less than the reciprocal of any parallel resistance (the denominator of the reciprocal of each parallel resistor). And because in the fraction, when the numerator is the same, the larger the denominator, the smaller the fraction, for example, 1 5 and 1 6 two fractions, the numerator is 1, the denominator 6 is larger than 5, so the fraction 1 6 is less than 1 5.

in series circuits.

Li: u=u1+u2

i=i1=i2

Because: u=ri

So: ri=r1i1+r2i1

Divide the two sides by i: to get, r=r1+r2

Conclusion: In a series circuit, the total resistance is equal to the sum of the resistances of each consumer.

In the connecting circuit: u=u1=u2

i=i1+i2

Because: i=u r

So: u r=u1 r1+u2 r2

Divide the two sides by U, 1 r = 1 r2 + 1 r2 Conclusion: parallel circuits.

, the reciprocal of the total resistance is equal to the sum of the reciprocal of the resistance of each electrical appliance.

The total resistance in a series circuit is equal to the sum of the resistances of the individual appliances.

That is: r string r1+r2+......rn。

The reciprocal of the total resistance in a parallel circuit is equal to the sum of the reciprocal resistance of each branch.

That is: 1 r and 1 r1 + 1 r2+......1/rn。

The total resistance in a series circuit is equal to the sum of the sub-resistors: r total = r1 + r2 + r3 + ......If there are n identical r in series, then r total = nr

The reciprocal of the total resistance in a parallel circuit is equal to the reciprocal sum of the individual sub-resistors:

1 r total = 1 r1 + 1 r2 + 1 r3 + ......If two resistors are connected in parallel, you can directly use the following equation to find :

Total r=r1r2 (r1+r2).

If n identical r in parallel, then r total = r n

1. Partial pressure formula:

The resistance of the supply voltage U resistance 1 is r1, and the resistance of resistance 2 is r2

Total current i=U (R1+R2).

The voltage divider on resistor 1 is u1=ir1=ur1 (r1+r2).

The partial voltage on resistor 2 is u2=ir2=ur2 (r1+r2).

2. Shunt formula:

Let R1 and R2 be connected in parallel, and the currents passing through them are I1 and I2

u1=u2i1r1=i2r2

i1/i2=r2/r1

i1/(i1+i2)=r2/(r1+r2) i2/(i1+i2)=r1/(r1+r2)

Let R1 and R2 be connected in series, and the voltages passing through them are U1 and U2

i1=i2u1/r1=u2/r2

u1/u2=r1/r2

u1/(u1+u2)=r1/(r1+r2) u2/(u1+u2)=r2/(r1+r2)

3. The principle of voltage division refers to the fact that in a series circuit, the current on each resistor is equal, and the sum of the voltages at both ends of each resistor is equal to the total voltage of the circuit. The formula for the partial pressure raw rubber operation is r1:r2=u1:u2. Shunt in parallel circuits.

4. The principle of series voltage division:

In a series circuit, the currents on each resistor are shown to be equal, and the sum of the voltages at each end of the resistor is equal to the total voltage of the circuit. It can be seen that the voltage on each resistor is less than the total voltage of the circuit, so the series resistors divide the voltage.

5. The principle of parallel shunt:

In a parallel circuit, the voltages across each resistor are equal, and the sum of the currents on each resistor is equal to the total current (dry circuit current). It can be seen that the current on each resistor is less than the total current (trunk current), so the shunt resistor is shunt.

Principle of partial pressure r1:r2=u1:u2

Shunt principle r1:r2= i 2:i 1

The principle of voltage division in series circuit: u1:u2=r1:r2

Shunt principle in parallel circuit: i1:i2=r2:r1

1) The formula for series-parallel connection of resistors is the same.

2) Series connection: The sum of the reciprocals of each sub-capacitance is equal to the reciprocal of the total capacitance 1 c1 + 1 c2 + 1 c3....1 c total.

3) Parallel: The sum of the subcapacitance is equal to the total capacitance C1+C2+C3....c Total.

In the first figure, the two points are connected in parallel in the circuit called the parallel resistor, and the circuit composed of a simple parallel resistor or electrical appliances (such as a television, a bridge air conditioner, a computer, etc.) is called a parallel circuit. Compared with the second disadvantaged circuit, the resistors (electrical appliances) are connected in series in turn.

Series connection: It is one of the basic ways to connect circuit components. Connect circuit components (e.g. resistors, capacitors, inductors, appliances, etc.)

Come one by one. Parallel: It is a connection between components, which is characterized by connecting two components and devices of the same or different models end-to-end.

The difference between the two: resistance series connection should refer to the series circuit, which refers to the circuit connection method in which the resistance is like a bead in the hail one after another. Resistor parallel connection should refer to parallel circuits, that is, in the circuit diagram, the connection form of resistors is parallel to each other.

Characteristics of series resistance: (1) The current flowing through each resistor is equal. (2) The total voltage at both ends of the series resistor is equal to the sum of the voltages at both ends of the resistor.

3) The total resistance of the series resistors is equal to the sum of the resistors. Characteristics of parallel resistors: (1) The voltage on each parallel resistor is the same.

2) The total current of the shunt resistor is equal to the sum of the currents flowing through the resistor. The equivalent resistance of the missing sail (3) parallel resistor is equal to the reciprocal of the sum of the reciprocals of each parallel resistor.