Question

Two bulbs of equal power are connected in parallel and they totally consume $110W$ at $220V$. The resistances of each bulb is:

• A. $550\Omega$
• B. $440\Omega$
• C. $330\Omega$
• D. $880\Omega$
• E. $660\Omega$

Answer 1

Answer: (D)

$880\Omega$

Bulbs are connected in parallel and thet totally consume $110W$ at $220V$.
Net power, $P_{net}=P_1+P_2$
$P+P=110$W $\{\because P_1=P_2=P\}$
$2P=110W\Rightarrow P=55W$
We know that,
$P=V^2/R$
$55=(220{)}^2/R$
$R=\frac{(220{)}^2}{55}=\frac{220\times 220}{55}=880\Omega$.