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My teacher asked a question and said to search about it.

We know that the power consumption of the resistance (wasted power) can be obtained by the following formula:

$$\begin{align} P &= I^2R \\ P &= \frac{V^2}{R} \end{align} $$

Now we know that in power transmission lines, electrical energy is transmitted with high voltage and low current so that energy loss is minimized (that is, the power consumption of wire resistance is minimized).

This issue is completely correct in the first formula, that is, as the current decreases, the power also decreases.

But in the second formula, this issue is not true, that is, according to the formula, with the increase in voltage, the power also increases, but our statement (which increases the voltage and decreases the current, decreases the power) is different.

What is the reason for this difference?

John Rennie
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BaRiboD
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  • The voltage loss in a transmission line is not the full voltage on the line (otherwise there would be no power left at the end of the line to actually perform useful work). V_loss=R*I and if you insert that into P_loss=V_loss^2/R, then you get the first formula back. Is that what you are asking? – FlatterMann Feb 02 '24 at 07:52

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