when Bulb of 40W and 200V is connected to another bulb of 80W and 150V in series, then which bulb will glow more brightly
Answers
There is no need of any calculation, let's make it simple.
To understand this you must first understand that the filament in a 40 watt bulb is thinner and therefore of higher resistance than the filament in a 60 watt bulb. In simple words it means that The bulb with "high power" will have "less resistance" always understand this fact.
Now coming to series and parallel connection of bulbs.
Means : In this question , if compare, 40 watt has higher resistance and 60 watt has less resistance. Got it. Now-
When connected in series:-
The current will be equal through each of the bulb.
But the voltage drop across each bulb will be different as connected in series. Of course the bulb with higher resistance will have higher voltage drop.
In this case it is - 40 Watt therefore it will glow brighter. (The same amount of current "squeezing" through the finer filament of the 40 watt bulb heats it more and make it glow brighter than the lower resistance 60 watt bulb.)
When connected in parallel:-
Here now, both of the bulb will have same voltage drop.
It is now very obvious that more current will flow through the bulb with less resistance and vice versa.
In this case it is - 60 watt therefore it will glow brighter.
In our homes the connection is in parallel configuration, so check in your house - the bulb with higher power is glowing more than the bulb with less power.