標題:
點解電纜要提升v來降低r
發問:
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點解電纜要提升v來降低r? 我想知的是原理 唔好答我P=V^2/R 所以提升v可以降低r
最佳解答:
電壓升高，電流會減少，所以energy lose(I^2*R)減少。 2006-10-29 12:53:52 補充： R不會降低！
其他解答:
By V=IR When voltage increases, current also increases. Resistance will not change. When the same amount of energy is needed to transfer from one place to another. Then if we use less time, less energy will be lost by going through the wire(resistance). Therefore電纜要提升v來降低r ...|||||In series circuit，current is the same for the whole circuit. As V=IR, if V increases, then I decreases since R is constant. As the power consumed by the wires(power lost) is given by P=(I^2)R, decreasing I will make P decrase and hence reduce the energy lost. 2006-10-29 13:08:25 補充： R is constant and it will not change.And we seldom use P=V^2/R to calculate the power consumed by the wires as we do not know the p.d. of the wires.
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