Question

Two lamps, one rated 220 V, 50 W and the other rated 220 V, 100 W, are connected in serieswith mains of 220 V. Explain why does the 50 W lamp consume more power

Answer 1

Resistance of 220 V, 50 w lamp is

`R_1` = `V^2/P_1` = `220^2/50` =968 Ω

Resistance of 220 V, 100 lamp is

`R_2` = `V^2/P_2` =  `220^2/100`  = 484  Ω

Since the two lamps are connected in series
So same current I passes through each lamp.
Power consumed in 220 v, 50 w lamp is `p_1 = I^2 R_1`
Power consumed in 220 v, 100 w lamp is  `p_2 = I^2 R_2`
Since `R_1 > R_2, P_1 > P_2`
i.e. 50 w lamp consumes more power.