eli5: how does AC power provide power when it’s just shifting back and forth? Don’t you need to have current going in one direction
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Consider a bicycle with fixed gearing and no free-wheeling — or perhaps a kid’s tricycle. Whenever it’s moving, the pedals are going up and down. And imagine your feet are clipped in so you can both push and pull on the pedals. If you push downward while the pedal is moving down, and pull upward whe the pedal is moving up, you can supply energy and make the bike/trike move uphill. But if you push downward while the pedal is moving up, and pull upward while the pedal is moving down, you’re removing energy from the bike/trike, and can make it slow down, or descend a hill gradually.
The key is the timing of the push/pull compared to the pedal’s motion. Similarly with electricity the direction of power flow depends on how the timing of voltage polarity and current direction relate. When the voltage is positive, power flows in the direction the current is flowing toward; when the voltage is negative, power flows in the direction the current is flowing away from. With a simple resistive load like a light bulb, the current will always flow in the direction that allows the resistor to absorb power. This is analogous to connecting a saw blade to the bike pedals — it resists both the push and the pull, so its timing always takes energy from the pedal.
Does current go one way in DC power? Electric cable is not a garden hose where you can cut the end and let the power flow out.
For DC power you have two wires, one for plus one for minus, in one current is toward load, the other away from load. In single phase AC you also have two wires, but instead of saying one wire is always plus and the other minus it switches constantly. [https://www.allaboutcircuits.com/uploads/articles/direct-and-alternating-current-ac-dc.png](https://www.allaboutcircuits.com/uploads/articles/direct-and-alternating-current-ac-dc.png)
Say you wanted a waterwheel to turn, it can turn just as much whether the river is flowing one way or the other.
Easier to think of electricity as something moving along a wire, and when the current stops it just stops moving, rather than disappearing.
It’s not a perfect analogy but that’s how it was explained to me.
For most electronics, you actually need DC power so you have those brick adapters (wall warts, etc). In a computer, the PSU (power supply unit) takes the AC and provides different DC power sources of different voltages.
If you didn’t know those convertors basically take the “negative” part of the sine wave an make it “positive” (ie; the absolute value of the voltage) and provide a steady DC voltage.
Other devices (AC motors, lights, fans, ovens, etc) don’t need DC and work great with AC.
Both a chain saw and a reciprocating saw can cut wood. The work/force/energy doesn’t have to go in only one direction.
well technically it IS flowing in 1 direction ; for a few milli/nano/pico-seconds XD ; and then it flows back in the other direction =] ; all modern equipment is just built to handle this constant reversal
and obvs AC is more dominate than DC becuz DC would require enormous wires to transmit power over the thousands of kilometers ; whereas AC only requires a very small wire and some transformers along the way
fun debate that drove the internet crazy awhile back : https://www.youtube.com/watch?v=iph500cPK28
The current is going in one direction, and then 1/120th of a second later it is going only the other way.
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