Question 620: Current Electricity

Question

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 :

Accepted Answer

(i) When all bulbs are 
glowing, from the given figure.
Equivalent resistance, R
eq
= $${R \over 3} + {R \over 3} = {{2R} \over 3}$$
Initial Power, (P
i
) = $${{3{E^2}} \over {2R}}$$ ......(1)
(ii) When two section A and one from section B are
glowing.
R
eq
= $${R \over 2} + R$$ = $${{3R} \over 2}$$
Final Power, (P
f
) = $${{2{E^2}} \over {3R}}$$
$$ 	herefore $$ $${{{P_i}} \over {{P_f}}} = {{3{E^2}} \over {2R}} 	imes {{3R} \over {2{E^2}}}$$ = 9 : 4

Answer

4 : 9

Answer

9 : 4

Answer

1 : 2

Answer

2 : 1

Current Electricity

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 :

Choose the correct answer: