The ac current does not flow in the same direction. electrons in the wire (and other components) simply move back and forth.
You know a joke where everyone is lining up for a photo? Instead of moving the camera to a corner, the photographer says, ok, can everyone move to the left? and the whole line of people is moving in the direction of no, all my people are moving to the right. other ways look better, everyone backs off.
well, the ac current flows like that. in North America, the current reverses its direction 60 times every second. The only important thing is there is a potential difference. the electrons are driven one or another with the difference.
light bulbs do not care which way the electrons move; Both directions, the filament heats up and becomes brighter. with AC current, voltage level constantly changing and reversing direction. think of the vertical path that your foot follows on the bike pedal. always backwards. up and down, up and down. always the number of different torques you can use – say you’re trying to start paddling up a steep hill:
do you prefer a crank pedal to point straight up or side to side?
Which crank position would you find easier?
ac as always changing in strength, and always reversing its path. in electronics there is an ac form that goes in only one direction, called ac fixed. but that’s all the other wax balls. have you ever pedaled the bike by pushing the pedal forward a bit, then backed up a bit, then repeated? ac that has been fixed is like that.
Well, sort of thing. electrons in the wire actually move quite slowly – in the power cord of a typical 120vac table lamp, they move slower than 10cm / hr (it depends on the size of the wire and the current being carried). with an ac frequency of 60 hz, this means the electrons in the circuit move about 15 microns before reversing direction-so in a fairly real sense, no electrons coming from the source make it near the powered device, let alone the actual load.
What travels quickly is the impulse of the electrons – because electrons in a small piece of wire are pushed from behind, they push the electrons in front of them, which push the electrons in front of them, and so on. that the impulse runs very fast – a very significant fraction of the speed of light (from ~ 50% to 99%, depending on the configuration). it’s like how water in pipes can flow more slowly than pressure waves (sound).
In ac circuits, the first electrons are pushed in one direction, and then pulled in the other direction (pulling on the electrons produces them pulling the electrons in front, just like the push action). so – even though the electrons barely move at all, they move forward and backward in concert – and that’s the current back and forth!
