I am no expert, but from what I have read, should a nuke be exploded over the US at the right altitude, most everything electronic will be non-functional and we will be back in the days of the early west. Iran has already successfully detonated a missile at emp altitude, which was categorized as a missile failure by our ignorant media, but that was exactly what they need to do to detonate an emp blast over North America. Should that happen, an Ipod will be the least of your worries.