Re: Basic
AC: A current is induced in a coil of wire by passing a magnet over the coil. In an alternator, each pole of the magnet passes the coil, and depending on which pole, a + or - voltage is created. Because the magnet is turning past the coils, each pole will pass by the coils, inducing a voltage which goes from zero to peak plus, back to zero, then to peak minus, and again back to zero at 360 degrees.
As far as shocks, I have heard that an AC shock tends to throw a person, while DC causes them to grip more tightly, but I'm not sure how true this is. I do remember back in the days of vacuum tubes, with their 350 volt power supplies, getting thrown across the room by a shock, though.
I hope this sheds some light on your question.
Regards,
Robert