In a certain city, electricity costs $0.19 per kW h. What is the annual cost for
ID: 1879367 • Letter: I
Question
In a certain city, electricity costs $0.19 per kW h. What is the annual cost for electricity to power a lamp- st for 5.00 hours per day with (a) a 100.-watt incandescent light bulb (b) an energy efficient 25-watt uorescent bulb that produces the same amount of light? Assume 1 year 365 days. (a) 100.-watt bulb (b) 25-watt bulb Number Number $20.075 $ 5.01875 Consider a cloudless day when the sun shines down across the United States. If 2293 kJ of energy reaches a square meter (m2) of the United States in one hour, how much total solar energy reaches the entire United States per hour? The entire area of the United States is 9,158,960 km2. Number kJ/hourExplanation / Answer
Q1.
a) total energy consumed by 100 watt incandescent light bulb
E=Pt
where P= power and t=time
E=(100 watt)* (5 h/day) * (365 days)
= 182500 watt hour
=182.5 kWh
Thus annual cost of the incadescent light bulb= 182.5 * 0.19 = $34.675
b)
total energy consumed by 25 watt fluorescent bulb
E=Pt
E=(25 watt)* (5 h/day) * (365 days)
= 45625 watt hour
=45.625 kWh
Thus annual cost of the incadescent light bulb =(45.625kWh) * ($0.19) = $8.669
Q2.
Energy per meter square
E= 2293 KJ/m2
Total energy = E* area
=(2293 KJ/m2)* (1958960 m2)
=4491895280 KJ