Idea 3of 4Builds onThe lever, not the amplifierThe toll
The squared term
Why half a million volts on the towers?
Today you'll discover
- what a long wire does to the current passing through it
- why the loss grows faster than the current
- the one dial the grid has
Think firstThe towers carry hundreds of kilovolts. Why?
The grid sends power at hundreds of kilovolts rather than a safe 120 V. Why?
Predict first, then drag the voltage. Watch the lost bar shrink with the square.
A step-up transformer with its volts, amps and watts printed on both sides. After a prediction, the transmission bench opens with a voltage slider and bars for the power delivered and the power lost as heat. The last step asks the loss when the voltage is ten times higher.
See the whole ideathe big idea and the key word, in one place
The big idea
Loss is I²R: the grid runs high volts and low amps.
Compare themP = V I: the power can ride high volts with low amps, or the reverse. Loss = I²R: the wire makes that choice for you.
Key word
- line loss
- the power a transmission wire turns into heat, I²R; kept small by sending the same power at high voltage and low current
About this modelVs ÷ Vp = Ns ÷ Np, and Vp Ip = Vs Is: a lever, not an amplifier. AC only, because only change induces.
Vs ÷ Vp = Ns ÷ Np, and Vp Ip = Vs Is: a lever, not an amplifier. AC only, because only change induces.
Ready to use it?
- Compare line losses for the same power sent at two voltages.