A 25 W, 220 V bulb and a 100 W, 220 V bulb are joined in series and connected to mains which bulb will glow brighter
Correct answer: A. 25 W
- A. 25 W
- B. 100 watt bulb
- C. First 20W and then 100 W bulb
- D. Neither bulb will glow
Explanation
Resistance of 25 W bulb is R25 =V2/P=(220)2/25=1936Ω Resistance of 100 W bulb is R100 =V2/P=(220)2/100=484ΩAs both bulbs are in series, current through them will be the same. But resistance of 25 W bulb is more. Hence, from the relation P=I2R, the 25 W bulb will glow more brightly.
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