Current Electricity and Electrical InstrumentHard
Question
If 2 bulbs rated 2.5 W − 110 V and 100 W − 110 V are connected in series to a 220 V supply then
Options
A.2.5 W bulb will fuse
B.100 W bulb will fuse
C.both will fuse
D.both will not fuse
Solution
R2.5 W = 
, R100W = 
⇒ R25 > R100.
P2.5 = i2 R2.5 , P100 = i2 R100
P2.5 > P100 due toR2.5 > R100 & Q P2.5 > 2.5W & P100 < 100 Ω (can be verified)
Therefore 2.5 W bulb will fuse
, R100W = ⇒ R25 > R100.P2.5 = i2 R2.5 , P100 = i2 R100
P2.5 > P100 due toR2.5 > R100 & Q P2.5 > 2.5W & P100 < 100 Ω (can be verified)
Therefore 2.5 W bulb will fuse
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