Wednesday, 16 November 2016

How is it possible to have high voltage and low current? It seems to contradict the relationship between current and voltage in E=IR



I have read different forums and watched a few youtubes (in addition to my textbook readings) and the explanations seem to fall short. The issue seems to be how we are first taught about a direct relationship between voltage and current (that is, an increase in voltage renders an increase in current if resistance remains the same) and then we're taught about power lines that have high voltage and low current (because other wise we would need thick wires that carry high current [which would run the risk of overheating due to the joule effect or something or another..). So please don't explain to me the infrastructural reasons why high voltage, low current is necessary for power lines. I just need to know how high voltage, low current is even possible. I've only been studying DC so far so maybe AC has rules that would enlighten me...but I thought the E=IR formula was universal.



Answer



You're confusing "high voltage" with "high voltage loss". Ohm's Law governs the loss of voltage across a resistance for a given current passing through it. Since the current is low, the voltage loss is correspondingly low.


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