The grid doesn't waste 70% of its power because voltage goes up
Power stations use transformers to step voltage up to hundreds of thousands of volts for transmission, which paradoxically reduces energy loss. The trick: doubling voltage quarters the current, and since loss scales with I², high voltage means minimal waste. Spin the generator and watch the transformer ratios respond in real time.
AC Generator
0 RPM • 0.0 V
Coil rotates in magnetic field, flux changes, EMF induced
ε = 0.0 V
Angular velocity ω
0 rad/s5 rad/s10 rad/s
Peak EMF
96 V
Frequency
0.64 Hz
Step-up transformers at power stations increase voltage to 275 kV or higher while decreasing current proportionally. Since power loss in transmission cables is I²R, reducing current by a factor of 100 cuts losses by a factor of 10,000. The transformer equation Vs/Vp = Ns/Np means if the secondary coil has 1000 times more turns than the primary, voltage multiplies by 1000. This only works with AC because the changing flux in the primary coil induces EMF in the secondary through mutual induction. DC would produce constant flux, zero induced voltage, and the transformer would be a useless lump of copper.
Know This
Generator EMF follows ε = BANω sin ωt for a rotating coil, creating sinusoidal output that transformers then step up (Vs/Vp = Ns/Np) to minimise I²R losses in long-distance transmission.