Question

Two electric bulbs marked 25 W-220 V and 100 W-220 V are connected in
(a) series and in (b) parallel, in turns, to a 220 V mains.
Which of the two bulbs will glow brighter in each case and why?​

Answer 1

Answer:

In parallel, both bulbs receive their rated voltage and therfore their rated wattage, so, no doubt the 100W will outshine the 25W.

In series it is a different story. Then both bulbs will receive equal amperage. In the dissipation equation, wattage equals I*I*R the amperages, I, are equal. So the dissipation, power, is proportional to resistance, which is 4 times higher for the 25W bulb. So it glows brighter.