Which bulb is brighter a 60W or 30W in a series then in parallel then separate circuits?

Answer 1

In series, a 30W incandescent lamp dissipates twice as much power as a 60W unit

designed for the same supply voltage. While it's difficult to estimate how much of

that power will be in the form of visible light and how much as heat, we're guessing

that their comparative visual brightnesses will track the total power dissipation of

each lamp, so the 30W will appear brighter than the 60W.

In parallel, or in separate, independent, unconnected circuits on separate power supplies,

the 60W lamp is brighter than the 30W unit designed for the same supply voltage.

Note: Plugging two bulbs into any two separate outlets in the same house

normally connects them in parallel.