Power Loss (from AAMC 6 - don't read if you haven't taken)

[LeoGer]

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Question: Electric power for transmission over long distances is 'stepped up' to a very high voltage in order:

a. to produce currents of higher density
b. to produce higher currents in the transmission wires
c. to make less insulation necessary
d. to cut down the heat loss in the transmission wires

Correct answer: D

I chose 'B' because V=IR, and at constant R, an increased voltage leads to an increase in current. I know that more power would be carried to the receiving end, but wouldn't more heat be lost in the transmission wire?

The answer key states that an increase in V allows for a decrease in I, thus (P=I^2R) less power is lost along the way. This seems backwards to me.

I appreciate any help in explaining this problem's reasoning.

 

[Rabolisk]

When a transformer is used to "step up", the power stays constant. P = IV, so as voltage goes up, current goes down. The rest is as the answer key describes it. If increasing voltage in this way also increased current.. well then electricity would be incredibly cheap.

 

[LeoGer]

Ahh, thank you.