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 times 10^4 hours, on the average and costs $12.0, whereas the incandescent bulb costs only 74.0 centsign, but lasts just 750 hours. The study assumed that electricity cost 7.00 centsign per kWh and that the bulbs were on for 4.0 h per day. What is the total cost (including the price of the bulbs) to run incandescent bulbs for 3.0 years? What is the total cost (including the price of the bulbs) to run compact fluorescent bulbs for 3.0 years? How much do you save over 3.0 years if you use a compact fluorescent bulb instead of an incandescent bulb? 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

Given,

Cost of compact bulbs is $12

Cost of ordinary bulb is 74 cents

a) Total hours incandescent bulb is on for 3 years

T = 3 x 4 x 365 = 4380 hours

but each bulb will be working for 750 hours

So, number of bulbs needed, N = 4380/750 = 6 bulbs

Energy Consumed by incandescent bubls for 3 years is

E = (100/1000) x 4 x (3 x 365) = 438 KWh

So, Cost = 438 x (7/100) + 6 x (74/100) = $35.10

b) Energy consumed by flourscent bulbs for 3 years is

E = (23/1000) x 4 x (3 x 365) = 100.74 KWh

So, Cost = 100.74 x (7/1000) + 12 = $12.705

c) Money saved = 35.10 - 12.705 = $22.40

d) Resistance of flouroscent bulb, R = V2/ P =1202/23

R = 626 ohms

(Please rate my answer if you find it helpful, good luck...)

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