如果相同電壓,但電流一個大一個細...

有兩個電路, 佢地各有一個電阻器,
其中一個電阻大一D, 只係會減電流,

一個係2A, 4V, 另一個係1A, 4V
即係2A戈個既燈光啲,
因爲2A x 4V = 8W, 1A x 4V = 4W

.夠簡單嗎?


其實係咪電流細, 個VOLTAGE跟住細埋??
你自己話既, 個VOLTAGE = 4V, 冇變到。

首先current系吳會「慢D」
只有大d同細d之別,
跟住清concept...

就你所舉的例子：
大家ge電壓都系4V
即V相同而固定不變
假設...
2A, 4V為第1個個案
1A, 4V為第2個個案

根據Ohm's Law：V = iR
where V= voltage ; i = current ; R= resistance

第1個個案 :
V = iR
由於V固定不變,
所以當 i 上升, R則會下降
以達致balance equation
i.e. V= i↑R↓

相反第二個個案：
情況相反
i.e. V= i↓R↑
以達致balance equation

由此可見,
「電流細,個VOLTAGE跟住細埋」這句話只符合一個條件：
就系resistance keep constant !

p.s.
1.燈光的光暗除左睇current
重要睇power
2. 請吳好嫌我長氣
因為我想你搞番清d concept

假設Circuit A 4V,2V,電阻器既電阻係2Ohm
假設Circuit B 4V,1V,電阻器既電阻係1Ohm
記住,
就算点改变電阻,
只会影響電流,
1D都吾關Voltage既!
除非你改变電壓,
令電流減少!
V=IR
Voltage = Current x Resistance

2009-09-22 22:41:28 補充：
By Using V=IR,
So That R=V/I

R=V/I Mean Where Resistance Remain Unchange,Than Voltage And Cuurent Is Proportional,In This Case,You Can Say "Voltage Decrease,So Current Decrease,Major Point Is Resistance Remain Unchange"

The specifications 2A, 4V or 1A, 4V only give the most optimium output of the resistances. It dpends whether the voltage requirement is met.
If the voltage applied to the resistance is less than 4V, the curent through it will be altered.
Anyway, Ohm's Law gives the relationship between voltage, current and resistance. It should be applicable to your situation.