Question

Out of two electric bulbs of 50W - 220V and 100W - 220V. Which one will glow brighter when they are connected (i) in series, and (ii) in parallel?

Answer 1

The resistance of the bulb is defined as R =V²/P So the resistance of 50W bulb is double than the resistance of 100W bulb. When they are connected in series the current through both bulbs is same. Hence 50-watt bulb will be brighter because P=I²R. In parallel, the voltage will be same in both bulbs. So, the 100-watt bulb will be brighter because of P=V²/R.