If two bulbs of `25 W and 100 W` rated at `220 V` are connected in series across a `440 V` supply, will both the bulbs fuse ? If not which one ?

Options

A. 100 watt bulb
B. 25 watt bulb
C. None of them
D. Both of them

Answer

B

Explanation

(b) Resistance of `25 W` bulb ` = (220 xx 220)/(25) = 1936 Omega`
Its safe current ` = (220)/(1936) = 0.11 amp`
Resistance of `100 W` bulb ` (220 xx 220)/(100) = 484 Omega`
Its safe current `= (220)/(484) = 0.48 amp`
When connected in series to `440 V` supply, then the
Current ` I = (440)/((1936 + 484)) = 0.18 amp`.