Question

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

• A. $200W,150W$
• B. $50W,200W$
• C. $50W,100W$
• D. $100W,50W$

Answer 1

Answer: (B)

When bulbs are connected in series with rated power $P_{1}$ and $P_{2}$ then total power consumption
$P_{S}=\frac{P_{1} P_{2}}{P_{1} + P_{2}}$
If bulbs are connected in parallel
$P_{P}=P_{1}+P_{2}$
so. $P_{S}=\frac{\left(\right. 100 \left.\right) \left(\right. 100 \left.\right)}{100 + 100}=50W$
$P_{P}=100+100=200W$