Question

Two bulbs when connected in parallel to a source take $60W$ each .The total power consumed when they are connected in series with the same source is

• A. $15W$
• B. $30W$
• C. $60W$
• D. $120W$

Answer 1

Answer: (B)

$30W$

$p_1=p_2=60W$, when bulbs are connected in series then total power
$P_s=\frac{P_1{P}_2}{P_1+P_2}$
$P_s=\frac{60\times 60}{60+60}$
$P_s=30W$