Question #11894

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

Expert's answer

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

R1 = U1^2 /

P1 = 120^2 / 100 = 144 Ohm

R2 = U2^2 / P2 = 120^2 / 10 = 1440 Ohm

Let's

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

P1 = (120 / (144

+ 1440))^2 * 144 = 0.8264 W

P2 = (120 / (144 + 1440))^2 * 1440 = 8.2644

W.

Answer: second bulb will consume more energy.

R1 = U1^2 /

P1 = 120^2 / 100 = 144 Ohm

R2 = U2^2 / P2 = 120^2 / 10 = 1440 Ohm

Let's

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

P1 = (120 / (144

+ 1440))^2 * 144 = 0.8264 W

P2 = (120 / (144 + 1440))^2 * 1440 = 8.2644

W.

Answer: second bulb will consume more energy.

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