If I have let’s say, 4 bulbs, each rated at 1.5 volts and they’re all connected in series.
Would my battery need to be rated 6 volts? My logic is that each bulb would have a voltage drop of 1.5 volts across them, but I’m not sure.
Like wise, if I put all the 1.5 volt bulbs in parallel with each other, is using a 1.5 volt battery okay as they would all share the same voltage?
Yes, your thinking of both series and parallel circuits are correct.
The total supply voltage of 6V is correct for 6V worth of 1.5V lamps in series, and total supply of 1.5V is correct for 1.5V lamps in parallel.
Yes, this is correct.
You can use a 1.5V power supply if you connect them in parallel.
With a series connection, beware that the bulbs must have the same resistance (so use the same type of bulbs). Otherwise, the voltage will be shared unevenly according to their resistance, and some bulbs will be overloaded and burn out, and some bulbs will be too dim. A parallel connection does not have this problem.
