Question

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 a.c. supply line. The power drawn by the combination in each case respectively will be :

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

Answer 1

The correct option is D $50watt,200watt$

If rated voltage $=$ supply voltage then use
$\frac{1}{P}=\frac{1}{P_1}+\frac{1}{P_2}$ (series connection) & $P=P_1+P_2$ (parallel connection)