Question

1. A fluorescent light bulb can replace an incandescent light bulb but it is more expensive to buy. 42W fluorescent bulb is considered to be equivalent to 150W incandescent bulb. The fluorescent light bulb cost 5$ while the incandescent one cost 1$. Price of electricity is 10c/kwh. Does it pay to replace? 2. For a gasification project, 50,000 tons of coal per day will be used to produce 50 million cft/day. What is the efficiency of the process? 3. Assume that your food intake constitute only of glucose - C6H1206. The digestion of glucose follows the following chemical reaction: CH1200 + 602 = 6CO2 + 6H20 +673kCal/mole. The molecular weights of these compounds are: Glucose - 180, Oxygen - 32, CO. - 44, H20 - 18. Your average caloric intake is 2000 kCal. Estimate your daily exchange of CO2. 4. How much coal will have the same heating value as 10 gallons of gasoline?

Answer 1

It saves money on replacing the incandescent bulb with the florescent bulb, The difference between the cost of two bulbs is 4$.

Fluorescent bulb consumes (150-42 )W less energy

= 108W

No of KwH require to overcome 4$=

4000/10=400Kwh

No of hours required to save that much amount= (400*1000)/108

=3703 hours approx Or 155 Days

Hence if fluorescent bulb is used more than 155 days than it does not pay extra