So for the transforming of voltage, a transformer could get a european outlet from 240 to 120 volts. How do these switch the frequency though, do they have to convert it into DC and then generate a signal back to AC? Or is there an easier way? Or do they just leave it at 50 hertz assuming everything is going to work properly?
Unless the frequency is critical to the operation of the device there is no attempt to change the frequency so all that is needed is a transformer with a 2: 1 ratio. Most devices simply change the AC to DC at a lower voltage. As the two frequencies are quite close there is usually no problem with circuit values.