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 1.00×104hours, on the average, and costs $11.0 , whereas the incandescent bulb costs only 74.0 ¢, but lasts just 750 hours. The study assumed that electricity cost 9.00 ¢ per kWh and that the bulbs were on for 4.0 h per day.

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

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

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

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

number of hours used = 3*365*4 = 4380

A)

number of incandescent bulbs required = N = 4380/750 = 6

energy consumed = E1 = 100*4*3*365 = 438000 wh = 438 kWh

cost c1 = (74*6) + 438*9 = 4386

B)

number of incandescent bulbs required = N = 4380/10^4 = 1

energy consumed = 23*4*3*365 = 100740 Wh = 100.7 kwh

c2 = 11+(100.7*9) = 917.3

(3)

save = C1-c2 = 3468.7

(4)

power = P = v^2/R

resistance = R = V^2/P = 120^2/23 = 626 ohms

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.