LED light bulbs are more energy efficient, last longer, cost more, and have a smaller environmental impact from manufacture to recycling or disposal. The question is which costs less: incandescent, compact fluorescent (CFL), or LED lights? (a) Ignore the time value of money. What is the average cost per hour for 25,000 hours of light-mg in a community with exist0.15/kWh electricity: for each choice?
(b) If the light is on 5%, 30%, or 60% of the time, how long until does it take for the 25,000 hours?
(c) Which type of light should a homeowner buy?

a) Cost_incandescent  = $ 375 , Cost _CFL = $ 75 , Cost_LED = $ 45

b)  total = 20833 days ,  total_day = 3472 days ,  Total_days = 1736 d

c) LED

Explanation:

This problem is interesting to solve it, we must have a very important factor, such as the equivalence of the light emitted by the three systems, let's perform the calculation for a light intensity of 1000 lumen in the three bulbs.

consumed potence

         incandescent 100W = fluorescent (CFL) 20W = Led 12 W

Now if we can solve your exercise

a) Let's find the power consumed by each type of bulb in the 25000 h

          E = P t

incandescent

             E_incandescent = 100 25000

             E_incandescent = 2.5 105 Wh

             E_incandescent = 2.5 103 kWh

Fluorescent (Low Power) CFL

               E_CFL = 20 25000

               E _DFL = 5 102 kWh

LED

               E_LED = 12 25000

               E_LED = 3 102 kwh

Let's use a direct rule of proportions (rule of three) for the cost of energy, if 1 kWh costs $ 0.15, the energy calculates how much it costs

incandescent

                 Cost_Incandescent = 2.5 103 kW / h ($ 0.15 / 1kWh)

                 Cost_incandescent = $ 3.75 102 = $ 375

CFL

                  Cost_CFL = 5 102 0.15

                  Cost _CFL = $ 75

LED

                  Cost_LED = 3 102 0.15

                   Cost_LED = $ 45

Here we do not take into account the possibility of burning incandescent bulbs and there is an extra replacement cost

b) for this part we use direct proportion rules

If the day has 24 hours and the light is on for 5%, how many days are 25000 hours?

     for 5% = 0.05

hours on in a day

         #_hoursdays = 24 hrs 0.05 = 1.2 hrs

total days

          total = 25000 / 1.2

          total = 20833 days

for 30% = 0.30

       # _hoursday = 24 0.30 = 7.2 h

       Total_days = 25000 h (1 day / 7.2 h)

        total_day = 3472 days

for 60% = 0.602

         #_hours = 24 0.60 = 14.4 h

         Total _days = 25000h (1day / 14.4 h)

          Total_days = 1736 d

c) you should decide between the CFL and the Led are much lower.

Between these two should take into account the cost of the bulbs, if we only take into account the cost of the energy consumed, the selection should be LED