Alternating Current (AC) vs Direct Current (DC)
The current (electric charge) only flows in one direction in case of DC. But in AC electric charge changes direction periodically. Not only current but also the voltage reverses because of the change in the current flow.
The AC versus DC debate personifies the War of Currents, as it is now called, in which the two giants of electric power were embroiled in the late 1890s. Thomas Edison, the proprietor of Direct Current, was so threatened by Tesla’s invention that, in order to discredit Alternating Current, he resorted to falsely misleading Americans. Apprehensive about losing his royalties to this new technology, Edison went so far as to electrocute an elephant to show Alternating Currents’ fatal dangers.
However, this did not stop Tesla from fulfilling his dream of powering the United States with cheap and highly efficient energy. Even now, we see long and thick wires tightly strung between soaring electrical towers like the strings of a guitar. AC took over the throne and reigned for a century, dominating households, offices and buildings, until now, when DC seems to be gradually making a comeback. Why did AC fare so well? And why might DC make a comeback?
Why is AC better?
Despite now having the technology to transmit DC over grids across long distances, we still persist to use AC. AC is pushed to higher voltages to overcome resistance, and when the power reaches the user, it is stepped down and rectified to power, for example, a computer. However, these technologies, like renewable technologies, not only cost a fortune, but their efficiency might also be questionable. Yes, DC provides stable outputs, but higher efficiency is achieved after eliminating losses.
Although the losses might be less than those incurred with AC, the step-up/down factor comes into play. The simplicity with which AC voltages can be modulated and transported is still unmatched, which is why AC might be still preferred. Both sources of power are excellent in their own ways, so determining who is triumphant would depend on the criteria under contention – the playing field. The judgment essentially relies on the application of the power.
Nowadays, both work in tandem. AC runs above us on wires, like the lines of an empty diary that terminate at your house. The AC voltage then is converted to DC with a rectifier, like the adaptor that your charger contains, to power household devices, such as bulbs, lamps and other appliances. The War of Currents might not be as dramatic as it once was, but it still subtly exists.