Why Are 2 Bulbs in Series Dimmer Than in Parallel?

[QotMMM]

Why would 2 bulbs in series be dimmer than 2 bulbs in parallel? I know bulbs in series have 1/2 the voltage, but compared to their parallel friends, they are getting twice the number of electrons passing through (i.e. the resistance is the same, right?) so ... why are they dimmer?

 

[Simon43254]

the resistance isn't the same. For bulbs in series the resistance is r=r1+r2.
Where as in parallel it is 1/rtotal=1/r1+1/r2. You can think of the bulbs as having a set resistor inside, because they're not the same as the surrounding circuit, so treat it as if they are resistors and not bulbs.