Question

a string of decoration light is formed by joining 22 bulbs of 12v each.when joined across 229v mains,the power consumption is found to be 26.4 w.calculate the redistance of each bulb

Answer 1

Answer: 120 Ω for 1 bulb

Explanation:

Power of 22 bulbs = 26.4W

Voltage of 1 bulb is 12V

Therefore voltage of 22 bulbs = 12x22= 264 (voltage is added in series)

Power = $voltage^{2}$/ R

26.4    =  264 x 264/ R

  R       =   264 x 264 /  26.4

  R     =  2640 Ω for 22 bulbs

Resistance of 1 bulb is 2640/22 = 120Ω

Hope this helps!!

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