Two 220 volt, 100 watt bulbs are connected first in series and then in parallel. Each time the combination is connected to a 220 volt ac supply line. The power drawn by the combination in each case respectively will be :

A
50 watt, 100 watt
B
100 watt, 50 watt
C
200 watt, 150 watt
D
50 watt, 200 watt

Solution:

If rated voltage = supply voltage then use $\frac{1}{P} = \frac{1}{P_{1}} + \frac{1}{P_{2}} = \frac{1}{100} + \frac{1}{100} = \frac{1}{50} \Rightarrow P = 50 W$ (series connection)

and P = P₁ + P₂ = 100+100 = 200 W (parallel connection)

Solution:

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