I understand AC is economic for transportation and easy to produce from converting mechanical energy into electrical energy. However, why don't electronics turn on and off because of this alternating nature of the current? For light bulb, maybe it does turn on and off and our eyes don't have fast enough *shutter speed* to capture the off moment so we are just seeing the average brightness of the light bulb. But what about computers? They did something to the battery so it doesn't turn off when current reaches its 0 point?