Edit: Sorry I meant just off of either AC Or DC
In: Engineering
DC is used for electronics because computer logic is based of the on or off state of a bunch of switches. Although, technically a bunch of switches turning on off at several megahertz like in your computer is AC, but nonetheless the power supply needs to be DC. DC is what batteries provide, and what is needed to charge them. Electrochemistry won’t force the chemical reaction to go back and forth several times a second. Imagine fire burning and then unburning, it just doesn’t work that way. DC is also what solar panels produce, and the way you need to drive LED lights without a horrible flicker.
AC relates well to rotating machines, aka motors and generators. Meaning AC is really easy to make a useful generator or low maintenance motor. Motors and generators work be trying to align an electromagnet with a magnet, or sometime a second electromagnetic. The thing about that, if you take two magnets, they only move towards each other once. Then it’s done. You have to pull them apart again. Not a great motor. AC works great for motor and generators because flipping the current flips the electromagnet, so two magnets can endlessly chase each other. DC can’t run a motor, unless you want to call a one way, one time use railgun a motor. A “DC” motor is really an AC motor. Switches (electronic or physical called a commutator) flip the current each time the motor turns half way. It’s fed DC, but really is AC. DC motors aren’t great though, they require metal brushes to get the current to the spinning part, which obviously wears out pretty quick. AC motors don’t need any metal brushes, they can just spin freely. The vast, vast majority of motors are what is called AC induction motors (they don’t have permanent magnet). They work really well with low maintenance. Factories use them, plants use them, the water coming out of your tap is pumped by them. This is what a masisve chunk of what all our electricity is used for, so it’s good to have an AC grid because it’s mostly used for motors.
AC also is the only thing that works with a transformer. It’s a really simple device consisting of two coils of wire next to each other, and as long as one coil has a different numbers of turns, the transformer can create a higher or lower voltage. Transformers are fundamental to the power grid, as you need high voltage, low current power transmission to do it efficiently. Low voltage is very wasteful and only good for end user applications. DC can’t work with a transformer, so you’re stuck at low voltage. There are modern high voltage DC power lines that offer some improvements over AC transmission lines. They still involve a transformer technically, just a conversion process between AC and DC. Basically, they need really big version of the cellphone charger you plug in the wall. These are expensive and only make it practical for very long, very high power transmission lines.
Latest Answers