Question

Out of the following bulbs rated 40 W, 220 V, 60 W, 220 V and 100 W, 220 V, which one will glow the brightest when connected in series to a supply of 220 V?

Answer 1

We now that,

P = \(\frac{V^2}{R}\)

R = \(\frac{V^2}{P}\)

Now, as all the bulbs are given the same voltage so resistance of the 40W bulb is the greatest.

As the bulbs are connected in series so the current through the bulbs are the same

P = i²R

So the power if the 40W bulb is the greatest and the power dissipated gives the glow of the bulb.