Question

When is (60w,220v) bulb and a (100w,20v) bulb are connected in series then which bulb will glow brighter?give u r answer wid proper explanation

Answer 1

When bulbs are in series the heat produced would be proportional to the current flow which is same for the two. In normal working of a bulb its resistance is

R=V^2/W

Resistance (R1)of 60W bulb is

R1=220×220/60Ohm=807Ohm

And resistance (R2) of the 20th bulb is

R2=(220×220/100)=484Ohm

If they are connected in series then energy dissipation rate is

H1=(I^2)R1=(220/(807+484))×807J/s=23W

(Since I=V/(R1+R2)=220/(807+484))

And, H2=I^2R2=((220/1291)×484)W=14W

Thus a 60W bulb gives more energy than a 100W bulb . Although the 60W bulb glow brighter than 100 bulb; but both give energy almost in infrared region.



hope this helps you

Answer 2

the bulb with power 60W and voltage 220V will glow more brighter