→ Beachboy:3Q 12/04 21:14
※ 引述《Beachboy (天煞孤星)》之銘言：
: 但實際上 從正極出發 到電阻之前 是不是還是有些許的電位下降?
Yes in reality.
No if you just consider this circuit diagram.
In a circuit diagram, a straight line has its resistance equal to zero.
It doesn't exactly correspond to a real metal wire, which still has some
resistance.
: 只是因為導線電阻很小 基本上都忽略不計
yes, if you are considering a real conducting wire.
: 可是如果換個想法
: 導線中應該也是有電場存在 電流順電場而下 電位降低
: 假設從電池 到 電阻 之間導線拉很長
: 那電位不也會下降很多嗎?
Yes, but the electric field will also change.
I am not sure what you are confused at, but practice the following, and
probably you will be clear..
The electric field is determined by the emf V of the battery.
V = V_wire + V_R
E_wire * d_wire = V_wire = I * R_wire
E_R * d_R = V_R = I * R
I = V / (R_wire + R)
I remember there are some similar problems in Halliday's
fundamentals of physics. ( Chapter ???? current and resistivity )
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