Current Electricity Charging Discharging Of Capacitors Question 461
Question: If two bulbs of wattage 25 and 100 respectively each rated at 220 volt are connected in series with the supply of 440 volt, then which bulbs will fuse
[MNR 1988]
Options:
A) 100 watt bulb
B) 25 watt bulb
C) None of them
D) Both of them
Show Answer
Answer:
Correct Answer: B
Solution:
Resistance of 25 W bulb $ =\frac{220\times 220}{25}=1936,\Omega $ Its safe current $ =\frac{220}{1936}=0.11amp. $ Resistance of 100 W bulb $ =\frac{220\times 220}{100}=484,\Omega $ Its safe current $ =\frac{220}{484}=0.48amp. $ When connected in series to 440 V supply, then the current $ I=\frac{440}{(1936+484)}=0.18,amp. $ Thus current is greater for 25 W bulb, so it will fuse.
BETA
