How do transformers make long-distance electricity transmission more efficient?

Transformers improve the efficiency of long-distance electricity transmission by enabling the use of high voltages, which minimizes energy loss.

When electricity travels through transmission lines, it encounters electrical resistance. This resistance causes some energy to be converted into heat, a phenomenon known as Joule heating. The power lost to this heating is calculated by the formula $P=I^{2}R$, where $I$ is the current and $R$ is the resistance.1

Because power loss is proportional to the square of the current, reducing the current significantly decreases these losses. Transformers allow power companies to step up the voltage to very high levels for transmission; since power is the product of voltage and current, increasing the voltage allows the same amount of power to be transmitted at a much lower current.23

At the destination, additional transformers step the voltage back down to safer, usable levels for homes and businesses. This process makes alternating current highly efficient for large-scale distribution over long distances.23