Question #11377

Two bulbs B1(40W,220V) and B2(100W,220V) are connected in series to an emf of 220 V. Which bulb will glow brighter?

Expert's answer

Let's find out the resistances of each bulb from the data given:

R1 = U1^2 /

P1 = 220^2 / 40 = 1210 Ohm

R2 = U2^2 / P2 = 220^2 / 100 = 484 Ohm

Let's

use P = I^2 * R for each bulb and find out if it is greater than

its power

rating. The one with higher power rating will get fused.

P1 = (220 / (1210 +

484))^2 * 1210 = 20.408 W

P2 = (220 / (1210 + 484))^2 * 484 = 8.163

W.

Answer: first bulb will glow brighter.

R1 = U1^2 /

P1 = 220^2 / 40 = 1210 Ohm

R2 = U2^2 / P2 = 220^2 / 100 = 484 Ohm

Let's

use P = I^2 * R for each bulb and find out if it is greater than

its power

rating. The one with higher power rating will get fused.

P1 = (220 / (1210 +

484))^2 * 1210 = 20.408 W

P2 = (220 / (1210 + 484))^2 * 484 = 8.163

W.

Answer: first bulb will glow brighter.

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