ความคิดเห็นที่ 13
You have to think that the network is the system.
And as N' thetorque said (believe him, he is the best in Physics), if you apply the current I to the system; finally, you will find R of the system.
I will explain my method using Kirchoff's current law.
Imagine that, between A and B, has the resistance Req.
Assume that, at point A, there is current I pass through this point.
From Kirchoff's current law, you can tell that each branch has current I/2 pass.
This is because the network is symmetry and must have I/2 + I/2 for entry and another I/2 + I/2 for exit.
Therefore, there is I/2 pass through each R.
Hence, the voltage between A-B is V = (I/2)*R = IR/2 ____(1)
Since we assume that we apply the current I though the system and the voltage between A-B is V.
Thus, from (1), We can say that our Req is equal to R/2.
In this case, R = 1 and our Req = 1/2 ohm.
Q.E.D.
จากคุณ :
Lueng  
- [
9 พ.ค. 50 13:40:09
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