interesting picture

[Rickabilly]

The 50Hz "ripple" can be seen on an incandescent bulb too, if you hook a high speed Cadmium Sulphate photo resistor up via a battery and measure the output on an oscilloscope but no where near as much as with a fluorescent tube or these days a compact fluorescent bulb (tricky little blighters look just like a proper bulb but strobe like a fluoro tube). Halogen spot lights whether high or low voltage, strobe less than even an old school bulb due to the thicker filament so use these on your work lights to get away from strobing issues.
Regards
Rick