Compact fluorescent bulbs are much more efficient at producing light than are or

Question

Compact fluorescent bulbs are much more efficient at producing light than are ordinary incandescent bulbs. They initially cost much more, but last far longer and use much less electricity. According to one study of these bulbs, a compact bulb that produces as much light as a 100 W incandescent bulb uses only 23.0 W of power. The compact bulb lasts 1.00×104 hours, on the average, and costs $ 12.0 , whereas the incandescent bulb costs only 74.0 ¢, but lasts just 750 hours. The study assumed that electricity cost 7.00 ¢ per kWh and that the bulbs were on for 4.0 h per day.

Part A

What is the total cost (including the price of the bulbs) to run incandescent bulbs for 3.0 years?

Part B

What is the total cost (including the price of the bulbs) to run compact fluorescent bulbs for 3.0 years?

Part C

How much do you save over 3.0 years if you use a compact fluorescent bulb instead of an incandescent bulb?

Part D

What is the resistance of a "100 W" fluorescent bulb? (Remember, it actually uses only 23 W of power and operates across 120 V.)

Explanation / Answer

here,

the total cost to run incandesentbulbs for 3 years , C = 7* 100*4*3*365 /1000 + 74 * ( 3 * 365 * 4 / 750)

C = 3498.16 cent

the total cost (including the price of the bulbs) to run incandescent bulbs for 3.0 years is 3498.16 cent

B)

the total cost (including the price of the bulbs) to run compact fluorescent bulbs for 3.0 years , C' = (3*365 * 4 * 23 * 7 /1000) + 1200 * 3*4*365 /(1*10^4)

C' = 1230.78 cent

C)

the saving when we use the compact bulb = C - C'

S = 3498.16 - 1230.78

S = 2267.38 cent

the savings when we use a compact fluoresent bulb instead of an incandescent bulb is 2267.38 cent

D)

let the resistance be R

V = 120 V

power used , P = 23 W

P = V^2/R

23 = 120^2 /R

R = 626.09 ohm

the resistance of the flourecent bulb is 626.09 ohm

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