Question

Three identical bulbs connected in series across an accumulator consumes $20W$ power. If the bulbs are connected in parallel to the same source, the power consumed is

• A. $20W$
• B. $60W$
• C. $90W$
• D. $120W$
• E. $180W$

Answer 1

The correct option is E $180W$

If $N$ bulbs are identical, then in series the total power
$P_{total}=\frac{P}{N}$
$20=\frac{P}{3}$
$P=60W$
Each bulb has power of $60W$.
In parallel combination,
$P=P_1+P_2+P_3$
$=60+60+60$
$=180W$