ac= +-+-+-+-+-+-+-+- osilation we use around 50 =60 hertz, pos neg current on same line defeats downfall at a better percentage than dc power
dc=direct current , no osilation.
our power system is worldwide ac power , something a man called Nicola Tesla gave us ac power, yet we all know who Edison is.......meh.....but thats a different story.....
u can have low voltage ac currents or high but usually for practical uses its needed to be converted back into dc for most appliences.
A tesla coil is fed ac power , but then thats why he created ac power, because nothing else could power it up as good or Efficiently.
l have pics of my toy tesla coil , thats fryed a mobile phone and watch l forgot l had on me , its located in my 2 bay shed obviosly on its own its only 20cm high, but far out can it output some voltage, l;l can get little pretty blue sparks between dozens of EMPTY beer cans, looks wikid , get a coil for electrical experimentation, BUT BE CAREFULL, they can KILL YOU , but you just learn and understand electricities properties better.......
enjoy.........