Physics and Electricity High School Questions: How does the number of electrical appliances paralle

The voltage is constant. Because the voltage at both ends of each appliance in the parallel circuit is equal, and the magnitude of the current depends on the resistance of the appliance itself. The formula for the total resistance of the parallel circuit is R1R2 divided by R1+R2, so the total resistance will become larger.

If I were to explain, I would think of a circuit as a waterway, where voltage is water pressure and current is water flow. The electrical appliance (resistance) is the water wheel. Well, start imagining.

Even if there are more water wheels in parallel, the total water pressure at both ends remains unchanged (the voltage does not change);

Finally, resistance doesn't have to think about it anymore, because it's easy to think that the more resistors in parallel, the smaller the total resistance.

I see? Thinking of a circuit as a waterway can also be applied to other analyses of Ohm's law problems similar to parallel and series circuits.

ps: If you want to write in another way, you should remember: series voltage division, parallel shunt. (Voltage distribution shunt refers to the voltage and current distributed by each electrical appliance).

PS of PS: Well, let me explain the reason why the electricity rush lights will be dimmed as said downstairs. Because a large number of resistors are connected in parallel during peak periods, the total resistance becomes very small, and the distributed voltage is also very small.

That's fine, right? The problem is that there are wires outside the house! The transmission line also has a resistance value, at this time, it is very large compared to the resistance of the branch, and the power consumed is also large, so at this time, the electrical appliances at home are actually working under light load (that is, working at a voltage slightly less than 220V).

So the lights will naturally be a little darker. ^

I have a different opinion, I don't know if it's right or not. When the number of electrical appliances (parallel) increases, the resistance, current, and voltage will decrease!

The above are theoretically unchanged, but in reality it is not the case, with facts to illustrate, usually 6 o'clock to 8 o'clock is the first time period of electricity, that is to say, there are many electrical appliances in parallel, we will find that the lights in our home will be darker, indicating that the voltage does not reach the rated voltage, and it is much lower. But if by 12 o'clock in the evening, there are fewer electrical appliances and fewer parallel connections, you will find that your lights are very bright, indicating that the voltage at this time is higher. Because the brightness is determined by the actual power, and the actual power is determined by the actual voltage, it implies that the voltage does not reach the rated voltage.

Therefore, the number of electrical appliances (parallel) increases, and the resistor, current, and voltage will decrease.

In parallel circuits, the voltage of each branch is equal, no matter how many are connected in parallel, the voltage remains the same! The more parallel connections, the smaller the equivalent total resistance and the greater the total current!

In fact, just remember one thing: whether you look at a single resistor or multiple resistors as a whole, the resistance increases, the voltage at both ends increases, and the current decreases!!

When the parallel resistance decreases, the series resistance increases.

Let R1 and R2 be connected in parallel in a circuit with voltage U, and the current allocated before turning on is I1 and I2, and the electrical power consumed.

is p1, p2, then:

1. The passing currents are inversely proportional to their resistance;

2. The current passing through them is proportional to the voltage at both ends of them;

3. The electrical power consumed is proportional to the passing current; Huihe.

4. The electrical power consumed is inversely proportional to the resistance they sell;

5、p1:p2＝r2:r1＝i1:i2

This is explained in two cases, as shown in the figure below

Figure 1: As the resistance of R1 increases, the current of R1 decreases while the current of R2 remains unchanged because the voltage at both ends of R1 and R2 is constant.

Fig. 2 R1 resistance increases, the equivalent resistance of R1 and R2 parallel circuits increases, the voltage V12 at both ends increases, V2 decreases, the current of R2 increases, and the current of R1 needs to be calculated (V12 R1). [It seems that the current of R1 is going to decrease, but the voltage of V12 is increasing, so it needs to be calculated].

Assuming that the power supply is regulated, then the voltage of the resistor does not change, the current flowing through it becomes smaller, and the voltage and current of the other resistor remain the same.

If there are two resistors in the parallel circuit, the resistance value of one resistor becomes larger, and the total resistance should also be increased accordingly, such as the power supplyNot an ideal voltage sourceThen the voltage at both ends of the resistor increases, and the current of the resistor becomes smaller and the current of the other resistor increases. Such as power supplyIt is an ideal voltage sourceThen the voltage at both ends of the resistor does not change, and the current of the other resistor decreases by increasing the resistance.

In the case of junior high school physics, the resistance becomes larger and the current becomes smaller when the power supply voltage remains the same; Because the parallel connection does not affect each other, the other resistance does not change!

Suppose there are two resistors, R1 and R2, when the R1 resistance becomes larger, the voltage on both ends of it does not change, and the current flowing through it decreases. The voltage and current of R2 do not change.

Connecting a new resistor in parallel increases the total cross-sectional area of the conductors in the circuit, thus reducing the total resistance. Because the magnitude of the resistance is inversely proportional to the cross-sectional area.

Since the supply voltage does not change, according to Ohm's law i=u r, the total resistance decreases and the total current increases.

It can be understood like this:

The parallel voltage remains unchanged, there are more branches, and the branch current is ix=u rx, then the total current is i=i1+i2+.ix, one more branch, the sum becomes larger, and the total current becomes larger.

Then we can find the total resistance using the parallel voltage and the parallel current.

r=u ii is increasing, but u is unchanged, then r decreases, so add a resistor to the parallel circuit, and the total resistance becomes smaller.

The total current of the handmill in the resistor parallel tremor circuit is equal to the current in each resistor ().

a.Equal. b.Sum (correct answer).

c. The difference. d.proportional.

The reciprocal of the total resistance in the parallel circuit is equal to the reciprocal sum of the parallel resistors, 1 r total = 1 r1 + 1 r2 ....... When the resistance of one of the resistors is increased, such as the resistance of r1, then the value of 1 r1 will decrease, then the total of 1 r will also decrease, and the total r will increase.

In a parallel circuit, the voltages at both ends of each resistor are equal, which is determined by p u*i u 2 r

i 2*r gives p1:p2 i1:i2 (i).

p1：p2＝r2：r1 （r）

Because the voltage at both ends of each resistor is equal, the ratio of power can only be expressed by the inverse ratio of resistance, or by the ratio of current, and the ratio of electrical power cannot be expressed by the ratio of voltage.

In fact, as long as Shi Chun remembers one thing: whether it is a single resistor or multiple resistors as a whole, the resistance increases, the voltage at both ends increases, and the current decreases!!

The virtual resistance of the parallel electric reputation is reduced, and the series resistance is increased.

in series circuits.

r total = r vertical + r ......i total = i = i ......u total = u + u i = u r, the formula is deformable, p=ui=i r=u rw=pt=uit=i rt=(u r)·t parallel circuit is being discussed.

The current method and the electric power and work are connected in series with the circuit.

1 r total = 1 r + 1 r, deformation laughing touch is r total = r ·r (r + r ).

i total = i = i ......

u total = u = u