*except lightbulbs and welders. maybe water heaters?
DC Transmission requires power stations to be closer together and more numerous Because the transmission lines heat-up and stretch. Also transmission lines, being wire, Have resistance. It is this resistance that causes heat and severe electrical losses. Hence, The need for more frequent power stations.
Edison (the thief) wanted DC power stations
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Oh yeah. And Marconi did not Invent radio nor did he send the first radio signal.
He was a thief too.
Tesla, The inventor of AC electric, received the first signal sent on equipment he invented.
Every bode else stole from the man.
(kelseymh) in the last paragraph, you mentioned that all of those things require ac power because of their motors. i have never seen an ac motor small enough to fit inside the hollow shell of a cd player, a vcr, or a dvd player. dc motors are not complicated to build, they use electromagnetism to turn. the only real problem i have seen with dc is with the transfer over long distances
Pretty well everything KMH says is actually wrong, in this "Best answer" !
Also, don't forget that it is far easier to change AC voltage and current of the supply to suit your needs than DC. AC can use a transformer, DC requires a much more complex circuit (with far more loss of efficiency).
Thermoelectric gave you the correct answer, but you could have found that out for yourself almost trivially (Wikipedia "alternating current").
More to the point, your assumption is very wrong. "Mostly everything" in a home environment, those devices which draw the majority of current, runs directly off of AC.
Everything with a motor -- refrigerator, washer, dryer, fans (including your furnace), air conditioner, swamp cooler, vacuum cleaner, hair dryer -- uses AC directly because motors driven by DC are more complex (and hence more expensive to build).
Anything which works simply by heat -- incandescent light bulbs, toasters, space heaters, hair dryers, etc. -- don't care whether they get AC or DC, and therefore it is easier (cheaper) to run them directly off wall power.
Television sets, VCRs and DVD players, CD players, all work off wall power because of either motors or high-voltage requirements.
AC and high voltage is the best way to get it from the Power station (very high voltage/low current) to your home (much lower voltage/much higher current available).
240v 50Hz also gives industry a standard to work to so that they can wind their transofmers topower your dc goods.
I have bypassed the internal ac to dc circuit in some bits of kit to run it off the car battery (after making sure the car battery can handle the current load/demand).
In Victorian times there were approx 250 leccy companies/generators all with different voltages and Hz - so you couldn't take your bits of leecy kit from one part of the country to another (and frequently different villages). It took an Act of Parliament to standardise it - the Industrial Revolution was dependent on a stable, consistent supply as goods were moved acrosss the country for the first time on a massive scale.
As Kevin says...
Or 120VAC, 60HZ if you live in the US.
Because you can't transfer DC over long distances without significant voltage drop.
how it gets to your home