Two bulbs B1 and B2 with ratings (10 W, 220 V) and (20 W, 220 V) respectively are connected in parallel across a 440 V input supply. Then what will happen to the bulbs
Two bulbs B1 and B2 with ratings (10 W, 220 V) and (20 W, 220 V) respectively are connected in parallel across a 440 V input supply. Then what will happen to the bulbs
Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Answer:
Two bulbs B1 and B2 with ratings (10 W, 220 V) and (20 W, 220 V) respectively are connected in parallel across a 440 V input supply. Then Both bulbs will fuse
Explanation:
Bulb on which voltage is greater than the rated voltage would fuse.
Sol. : Since both bulbs are connected in parallel, the voltage across every bulb will be 440 V. Thus, both bulbs will fuse.
☆☆
Both the bulbs has a voltage rating is 220 V, thus voltage remains constant in both the cases.
The bulb that has a lower power rating will have higher resistance, whereas both the bulbs are connected in series.
Hence, both the resistances will combine into one.
Resistance= Voltage²/ Power
R-25= 220²/25=1936 Ohms.
R-100= 220²/100 = 484 Ohms.
Since, both the bulb are in series, total resistance = 1936+484 =2420 Ohm
Voltage=Current×Resistance
For 440 V, current is:
440 V/2420 Ohm= 0.1818 Amp
Voltage across 25 W bulb will be = Current × resistance of 25W bulb
= 0.1818 × 1936 = 352 Volts.
Voltage across 100 W bulb will be =Current × resistance of 100 W bulb
= 0.1818 × 484 = 88 Volts
In a series connection, the equipment with higher resistance have to bear more voltage.
Thus, the 25W bulb will fuse first.
☆☆
☆☆