1) In a certain city, electricity costs $0.20 per kW·h. What is the annual cost
ID: 884975 • Letter: 1
Question
1) In a certain city, electricity costs $0.20 per kW·h. What is the annual cost for electricity to power a lamp-post for 5.00 hours per day with (a) a 100.-watt incandescent light bulb (b) an energy efficient 25-watt fluorescent bulb that produces the same amount of light? Assume 1 year = 365 days.
(c) A typical incandescent bulb costs $0.89 and lasts for about a year; a typical energy efficient fluorescent bulb costs about $3.49 and lasts for about 3 years. Is the additional cost of the fluorescent bulb justified?
Explanation / Answer
a) electricity cost = 0.2 KW.h
electricity cost consumption per day = 100*5 = 500 watt.h
electricity cost consumption per year = 500*365
= 182.5 kwatt.h
electricity bill per year = 182.5*0.2 = 36.5 dolar
b ) energy efficient 25-watt fluorescent bulb bill per year = 1/4*36.5 = 9.125 dollar
c) the cost of efficient fluorescent bulb is 4 times higher than incandescent bulb . so it justified.
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