Question

Two bulbs of 40 W and 60 W are connected in series to an external potential difference. Which bulb will glow brighter? Why?

Answer 1

Given: Two bulbs of $40W$ and $60W$ are connected in series to an external potential difference.

To find which bulb will glow brighter and why

Solution:

When two bulbs are connected in series, the current, I will be the same.

But the resistance varies. Higher the resistance, brighter the glowing.

$P=\frac{V^2}{R}⟹P,R$ are inversely proportional to each other.

Hence, $P_{40}<P_{60}⟹R_{40}>R_{60}$

So, the resistance of $40W$ bulb is higher than the $60W$ bulb.

Hence, $40W$ bulb will glow brighter.