Theoretically, why does the ideal transformer P2 decide P1?

The ideal transformer has no energy loss, so it is said that the voltage of the primary coil u1 determines the voltage of the secondary coil u2, because the electromotive force of the secondary stage itself The electrical energy comes from the primary. Therefore, this conclusion is correct.

Electrical energy is a real substance, and its biggest holding point is that it can be transferred and cannot be stored at low cost, so it can be supplied by the generator as much as the load is used. Therefore, this conclusion is also correct.

It is precisely because there is no other orientation to the energy of the ideal transformer, and the fact that the electrical energy can be transferred and cannot be stored, that the size of the load power determines the amount of power that the generator only needs to provide. On the transformer, only the lossless transfer of electrical energy takes place.

The power generated by the generator is used as much as the number of coils is used. It refers to how much power is available for the transformer in the process of lossless transfer of electric energy on the transformer, and how much power can be used in the secondary. However, the amount of primary power for the system is determined by the secondary load.

The contradiction you are talking about is actually caused by the wrong foothold in your view of the problem, and it is because you have misunderstood these two concepts.

Why does P2 decide on P1 and give as much as you want?

There's nothing wrong with that. The secondary side needs 100W, and the primary side provides 100W; 1000W is required on the secondary side, and 1000W is provided on the primary side (provided that the transformer power allows).

If the primary side can provide 1000W, and the secondary side only uses 100W, then 900W** goes? In fact, this 900w is not necessary to be generated at all. In fact, it reduces the burden on the generator.

Hello! In transformers with large capacities, the DC resistance is almost negligible, only a few ohms or tens of ohms.

Of course, the no-load loss is to check whether the quality of the iron core is qualified, and the positive or negative of P1 and P2 is because the initial phase angle of the average power, voltage, and current should be kept slightly in the same direction.

When using the two-watt meter method to measure power, the actual power is the algebraic sum of the two meters, and the transformer should use a watt meter with a low power factor when measuring no-load.

It's simple!

Since the voltage u1 does not change, the power p1 = (u1) 2 r1 on the resistor r1 does not change!

Obviously, it can't affect the electricity consumption of my home just because the neighbor's house turns on and off the electrical appliances, right?! What do you say, landlord?

(1) Voltage constraints.

When the transformer comes to the original and secondary lines.

When the number of turns of the source is fixed, the output voltage is determined by the input voltage, that is, it can be simply described as "voltage primordial limiting voltage pair".

2) Current constraints.

When the ratio of turns between the primary and secondary coils of the transformer is constant, and the input voltage is determined, the current in the primary coil is determined by the output current in the secondary coil, that is, it can be briefly described as "the current secondary restricts the current original".

3) Power constraints.

The output power p2 determines the input power p1. The input power p1 of an ideal transformer is equal to the output power p2. Under the condition that the input voltage U1 and the output voltage U2 are certain, when the load resistance r decreases and increases, and the output power increases, the input power also increases; Conversely, when the load resistance r increases, it decreases and the output power decreases, and the input power also decreases.

In layman's terms, it is "how much to use, how much to give, not how much to give, how much to use".

a, c, the current ratio is inversely proportional to the turns ratio, the input power is equal to the output power, so i1 is determined by i2, and p1 is determined by p2, so a is wrong, c is correct;

B, U2 is determined by the ratio of input voltage and turns, and has nothing to do with the load, so B is wrong;

d. The input power and output power of the ideal transformer are equal, so D is wrong;

Therefore, c

P2 is the highest, P1 is just a preliminary estimate of your score, and P3 is the upper limit of the decision.

P1, P2 account for a large proportion, P3 accounts for a small proportion, (I**you have a high score) professional IELTS**.

That's a strange question you're asking...

Why do you focus on which part has a high weight? Do you do your best for the one with a higher specific gravity, and you do your best with a slightly lower specific gravity?

Each of these parts has the potential to affect the overall ... And your answers will affect the examiner's judgment of you.

Maybe you're wondering which part has a low weight, and you can make a slight mistake, it doesn't matter. But in such a subjective exam, how can there be an absolute division?