quiz lesson 3

# An efficiency of about 20

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Unformatted text preview: 6 x 10^6 Joules of energy are lost through unburnt fuel. The boiler radiates 1.4 million Joules to the atmosphere. What is the efficiency of the boiler in percentage? Correct A ) 58.9 Energy efficiency = Useful energy output / Total energy input Useful energy output = 18 - 6 - 1.4 = 10.6 million Joules Efficiency of the boiler = 10.6 / 18 x 100 = 58.88% Three energy conversion processes take place in succession. The first has an efficiency of 67%, the second is 31% efficient, and the third 5%. What is the efficiency of the entire process? Correct C ) 1.04% Overall Efficiency = 0.67 x 0.31 x 0.05 = 0.0104 = 1.04% Which one of the following is a list of devices from the most efficient to least efficient in that order? Correct B ) Power Plant (thermal), Automobile Engine, Light- bulb (Fluorescent), Light- bulb (Incandescent) Incandescent Light- Bulb (5%), Fluorescent Light- Bulb (20%), Electric Motor (90%), Power Plant (35%), Automobile Engine (25%), Home oil Furnace (80%) In a heat engine what type of energy is converted to mechanical energy? Correct A ) Thermal A heat engine is defined as a device that converts heat energy into mechanical energy. Which one of the following energy conversion devices has the highest energy efficiency? Correct D ) Generator Generator has an efficiency of 97%, Steam turbine has an efficiency of 40%, Automobile engine has an efficiency of 25% and Incandescent light bulb has an efficiency of 5% The following step efficiencies apply to the use of gasoline in a car: Crude production: 94%, Transportation 94%, Refining 93%, Distribution of gasoline 97%, Engine efficiency 24%. What is the overall efficiency of the process in percentage? Correct A ) 19.1 Overall Efficiency = 0.94 x 0.94 x 0.93 x 0.97 x 0.24 x 100 = 19.13% Which one of the following energy conversion devices has the highest energy efficiency? Correct D ) Steam boiler in a power plant Steam boiler in a power plant has en efficiency of 88%, Steam turbine has an efficiency of 40%, Automobile efficiency of 25% and Fluorescent light bulb has an efficiency of 20% The following...
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