Question

Two bulbs `A and B` are rated `100W - 120 V and 10 W - 120 V` respectively. They are connected across a `120 V` source in series. Which will consume more energy ?

Answer 1

Correct Answer - `0.83 A, 0.083 A, Bulb A`
Resistance of bulb A, i.e., `R_1 = (V^2)/(P_1) = ((120)^2)/(100 W) = 144 Omega`
Resistance of bulb B, i.e., `R_2 = (V^2)/(P_2) = ((120 V)^2)/(10 W) = 1440 Omega`
Current through bulb A, i.e., `I_1 = (V)/(R_1) = (120 V)/(144 Omega) = 0.83 A`
Current through bulb B, i.e., `I_2 = (V)/(R_2)=(120 V)/(1440 Omega) = 0.083 A`
Bulb A (of 100 W) will consume more energy than the bulb A (of 10 W) when these are connected in parallel.