天同師兄,請問有關你的回答

用戶2457

2011-04-10 9:32 am

天同師兄,想請問有關你於
http://hk.knowledge.yahoo.com/question/question?qid=7011040900861
中的回答:

你提出Statement (3) is wrong.

The capaciotr is neither charging or discharging when its two terminals are at the same potential. Hence statement (3) is wrong.

但請問:

圖片參考：http://imgcld.yimg.com/8/n/HA00270495/o/701104100016713873423951.jpg

Q: When switch S closed ,cap is changing,at T=t tands to zero,charge on cap=0,potentialof cap =0,is my statment correct ? If it is correct,is it contradict to your ans,thx for ans!

回答 (1)

天同

2011-04-10 6:25 pm

✔ 最佳答案

The two situations are different.

In the earlier problem, I suppose the voltages so given are those that at "steady state". That is, all these voltages do not change with time. If not, then you really could not tell anything, as you do not know what would happen in the next second, given that you are only provided with part of the circuit in the question.

The situation in this post is a "transient state" and the whole circuit is given. You could definitely tell what is going to happen.

Be aware that although the voltage across the capacitor is zero at t= 0, this situation only occurs, in theory, at an instant of time.

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