Can 2 light bulbs of 120V in series be used on 230V AC?
It is possible, as long as they use the same power (or resistance).

However, it comes at a risk. If one of the bulbs uses less power (for whatever reason, maybe damaged/end of light ... see Ferrybig's remark below for a good reason), the other uses more, and will break (faster), so it's not a perfect solution.

Because of P = V * I &lt;=> 150 = 110 * I, I = 1.36 A for two bulbs, which is 0.68 A per bulb.

For the 220V way: P = V * I &lt;=> 150 = 220 * I, I = 0.68 A per bulb.