Three electric bulbs of $200\,W,\,\,200\,W$ and $400\,W$ are shown in figure. The resultant power of the combination is ................ $W$
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Bulbs $\mathrm{A}$ and $\mathrm{B}$ are in parallel, their effective power is
$P^{\prime}=P_{A}+P_{B}=200 \mathrm{\,W}+200 \mathrm{\,W}=400 \mathrm{\,W}$
$\mathrm{P}$ and bulb $\mathrm{C}$ are in series, the resultant power of the combination is
$P_{R}=\frac{P \times P_{C}}{P+P_{C}}=\frac{400 \mathrm{\,W} \times 400 \mathrm{\,W}}{400 \mathrm{\,W}+400 \mathrm{\,W}}=200 \mathrm{\,W}$
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