Question

Two bulbs of 70 W and 50 W are connected in parallel to an external potential difference. Which bulb will glow brighter? Why?

Answer 1

Given: Two bulbs of $70W$ and $50W$ are connected in parallel to an external potential difference.

To find which bulb will glow brighter and why

Solution:

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

Hence, $P_{50}<P_{70}⟹R_{50}>R_{70}$

So, the resistance of $50W$ bulb is higher than the $70W$ bulb.

When two bulbs are connected in parallel, the Voltage across both the bulb will be the same, so smaller resistance bulb will glow brighter.

Hence, $50W$ bulb will glow brighter.