I was wondering if there is a way, other than an oscilloscope, for testing frequency? Like would a standard incandescent light bulb/fixture flicker at 50 hertz? Something like that. Thanks.
If it has a frequency counter, it will say it somewhere. Mine is a TES brand, and have a Hz position to count frequency, but isn't very reliable. It seems to work ok with a square wave.
You can see the Hz position in this one: http://cp.home.agilent.com/upload/cmc_upload/U1252B_800x1204.jpg
Be careful- As long as you know you have have nice waveforms or nice pulses, a frequency counter is great. If you're looking at garbage like auto ignitions, a scope might be better.
The best of both worlds is a scope with a built in frequency counter.
An old method (from the early 1900's) was to put a strong magnet next to the filament of an incandescent lamp. If the hot wire got kind of "fuzzy", you'd know it was being driven by an AC voltage rather than a DC voltage. It obviously won't measure the frequency without some help though.
There were also frequency meters that had tuned thingies that vibrated near the line frequency. There would be a row of them that would e.g. let you monitor frequencies near the line frequency. I've got one somewhere out in the shop, but I'm too lazy to go get it and write down the model/name...
True frequency counters are the best for careful measurement, but are usually beyond the needs of the average hobbyist. Modern DMMs often have a frequency measurement (even my 20 year old Fluke 83 does). Modern digital scopes are pretty good too, as they can be set to both show the waveform and measure its frequency.