In ac systems phase has everything to do with how much power is delivered.
For sine waves the rms value of a voltage or current is root(2)/2 = 0.707 of the peak value of the voltage or current. For other wave shapes rms can be calculated from a formula (wait for it) that calculates the square root of the mean of the square of the voltage or current waveform.
dude, pick a damn stove! you can buy what you like!
yer smartphone run on AC?..
Tesla was brilliant (i think edison was a jerk) but they are different animals in the same cage