How many spanish speakers does it take to change a light bulb?
hehe... Couldn´t help it, sorry.
There are a lot of delightful jokes here:
The most fun I've ever had while translating :-)
But "bombita" is a synonym I find mostly in informative/advertising texts not so much in everyday speech, and the same goes for "lamparita". I usually hear people say "foco", which is the way I call it, and this word is also used in informative/advertising/etc. articles.
EDIT: ours is a big country, that's all, we call things differently from one region to another.
I suspect it is similar to how in the U. S. you can tell what region someone is from by what they call 'soda'. In the North it is 'soda', which is more correct, maybe more formal. Some áreas would be 'pop' or 'soda pop'. Best of all the infamous southern conversation "You want a Coke? What kind? " "Pepsi". I don't really know the details, I've never had soda and don't pay attention. But I hear people talk about this subject a lot. All are correct in that yes you can use them and people will understand you.
That reminds me of the cartoon by a famous hispanic artist, Lalo Alcaraz, he wrote this punch line, based on the theme: An Army of One, but for hispanics this would be: An Army of Juan. http://laloalcaraz.com/la-cucaracha-bug-blog-vs-alabama-un-pinche-comic-by-lalo-alcaraz
We don't have Jamal in the Hispanic world. And the meaning of Juan is John. So... John Doe, or John Smith, is equivalent to Juan Perez. This is an interesting topic, so I checked on wikipedia and found this link: http://es.wikipedia.org/wiki/Sin_nombre (in spanish) or ---http://en.wikipedia.org/wiki/John_Doe (in english)