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# Confused with current, voltage and resistance Watch

1. In physics unit one it states that in transmission lines:
Transmission lines
In step-up transformers the voltage is increased which reduces the current.
Transmission lines have a high resistance and the current warms the transmission wires.

In physics unit two it states that:
As voltage increases current increases.
As voltage increases resistance increases- so wouldn’t that increase the heat????
REALLY confused!
2. Current heats up the transmission lines – voltage has increased, but current has decreased.
3. I thought an increase in voltage increased the current?
4. Ah, you use the equation

power = current x voltage (P=IV)

So, when you pass the same power through a power line...
Say I = 10 A and V = 2 V
P = 10 A x 2 V
P = 20 W

Now, if we step up the voltage – let's times it by 10 (remember that power will stay constant in this scenario)
20 W = I x 20 V
I = 1 A

So current has decreased.

That's the logic of power transmission anyway.
5. THANKS! MEANS A LOT! )

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Updated: April 16, 2014
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