電路問題一則 關於電壓

你的想法是對的, 任何的電路有負載就有電壓降, 就算是0.0001V也是電壓降, 所以電路設計一定要計算電壓降的, 還有就是電源的内阻(就算是乾電池也有内阻), 也會有導致電壓降的機會, 你的結論就是燈泡完整吸收20V的電壓是不對的, 可能是19.9999V

Just think of a battery as a source supplying charges. The +ve pole of a battery has an accumulation of +ve charges, thus possesses a +ve potential. The -ve pole of the battery has an accumulation of -ve charges, thus has a -ve potential. The +ve potential at the +ve pole and the -ve potential at the -ve pole then constitute the emf (electromotive force) of the battery.

When a light bulb is now connected to the battery, one end to the +ve pole and the other end to the -ve pole. The bulb then acquires +ve charge from the +ve pole and -ve charge from the -ve pole. Because these are the same charges as those originally in the battery, the potential difference (or voltage) across the bulb should also be the same as that of the battetry. Hence, a 10-volt battery will supply 10 volts across a bulb that is connected to it.

你可以參考以下


http://en.wikipedia.org/wiki/Maximum_power_transfer_theorem