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

Answer

B

Explanation

Case I: All bulbs are glowing
`R_(eq)=(R )/(3) +(R )/(3) =(2R)/(3)`
Case II: Two from section A and one from section
B are glowing.

`R_(eq)=(R )/(2) +R =(3R)/(2)`
Here `P prop (1)/(R_(eq))`
`:. (P_(i))/(P_(r ))(3R//2)/(2R//3)=(9)/(4)`