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[Phys-L] Power loss in transmission lines



Hi,

I suppose that the power loss in transmission lines is part of most intro courses on E&M. The basic idea is quite clear: given a certain produced power, the greater the voltage the smaller the current is, which means the smaller power loss in the transmission lines. So far so good. We had a simple quantitative calculation on the power loss and I casually asked my students check the case when the voltage is pretty low. This gave a nonsensical answer. I looked at the situation,and quickly derived a formula of the loss fraction. The same formula can be found here: <http://www.bsharp.org/physics/transmission> (Scroll down to the section "High-Voltage Transmission Lines").

What bothers me is that the loss fraction can conceivably be one or even more, which is clearly not physical. Perhaps I am missing something?

Regards,

Antti
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