Maybe jarrettph misunderstood my original question. The word "light" in English covers both the light emitted from electrical devices and from the sun. My question was whether "ljus" covers the same semantic camp as English, in addition to including the meaning of "candle".
I'll try to summarise to make it clearer:
- ljus by itself is either "candle(s)" or the light emitted from any source
- to turn the lights on and off, you can refer to them as ljus, usually in the definite form ljuset
- when buying lights, Swedish never uses ljus but rather the physical item you're buying: lamps, lightbulbs, etc.