Question

In the circuit all bulbs consume same power .If resistance of bulb 1 is 36 ohm then resistance of bulb 3 and 4 are??
Bulb 2 and 3 are in series ,their combination is in parallel with bulb 1 and this whole is in series with bulb 4 ...

1)4,12ohm
2)4,9ohm
3) 9,4ohm
4) 9,9ohm

Answer 1

Answer:

9,4ohm

Explanation:

In the circuit all bulbs consume same power .If resistance of bulb 1 is 36 ohm then resistance of bulb 3 and 4 are??

Bulb 2 and 3 are in series ,their combination is in parallel with bulb 1 and this whole is in series with bulb 4 ...

1)4,12ohm

2)4,9ohm

3) 9,4ohm

4) 9,9ohm

2 & 3 Bulbs are in series and consume same power

so their resistance is same

so let say resistance of bulb 2 & Bulb 3 = R₃ Ω

R₃ + R₃  = 2R₃

2R₃ is in parallel with bulb1  36 Ω

so their net resistance =   1/(1/2R₃ + 1/36)

= 36R₃/(18 + R₃)

as this resistance is of three bulbs so 1/3  times this should be equal to bulb 4 resistance = R₄ Ω

=> R₄ = 36R₃/3(18 + R₃)

=> R₄ = 12R₃/(18 + R₃)

R₃ = 9Ω  & R₄ = 4Ω