Six similar bulbs are connected as shown in the figure with a DC source of emf E and zero internal 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-[NEET 5-5-2019]
A)1 : 2
B)2 : 1
C)4 : 9
D)9 : 4
Correct Answer:
D
Solution :
When all bulbs are glowing \[{{R}_{eq}}=\frac{R}{3}+\frac{R}{3}=\frac{2R}{3}\] \[Power\,{{P}_{1}}=\frac{3{{E}^{2}}}{2R}\]----------------- (i) In case two \[{{R}_{eq}}=\frac{3R}{2}\] \[Power\,{{P}_{2}}=\frac{2{{E}^{2}}}{3R}\]--------------- (ii) \[\frac{{{P}_{1}}}{{{P}_{2}}}=\frac{3}{2}\times \frac{3}{2}=\frac{9}{4}\]