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

Hint: To solve this problem we have to check what the series and parallel connection means.
If bulbs are connected in series then their total power is the addition of respective but for the case of parallel only the addition of power of reciprocal is the total power consumed value so we can solve the power consumption.

Complete step by step answer:
If N bulbs are identical then the total power is,
${P_{total}} = \dfrac{P}{N}$

In this problem 3 bulbs are corrected.

Then in series the total power
$
  20 = \dfrac{P}{3} \\
  P = 60W \\
 $

60W is the power of each bulb.

Now the bulbs are corrected parallel

$
  P = {P_1} + {P_2} + {P_3} \\
   = 60 + 60 + 60 \\
   = 180W \\
 $
$ \therefore$ The power consumed is 180 W.

So, the correct answer is “Option E”.

Note:
As three bulbs are identical so we can say the power consumed by each is equal so we have taken in this problem but if all bulbs are not identical then we have to find three power respectively to solve the problem then we can find the value of power for parallel connection always number parallel connection create more power that series connection.