Six similar bulbs are connected as shown in the figure with a DC source of emf E, and zero intermal resistance.
The ratio of power consumption by the bulbs when (i) all are glowing and (ii) in the situation when two from section A and one from section B are glowing, will be:

Options

A. `2:1`
B. `4:9`
C. `9:4`
D. `1:2`

Answer

C

Explanation

`R_(eq) = R + R/2 = (3R)/2`
`i=E((3R)/2) =(2E)/(3R)`
`P_(2) = i^(2)R_(eq) =((2E)/(3R))^(2) = (2E^(2))/(3R^(2))R`
`P_(1)/P_(2) = 9/4`