EGEE
A 106 watt incandescent light bulb is operated for 89 hours, and a 18 watt LED light bulb is operated for the same period of time. At 0.05 dollars per kWh, what is the cost savings (units of $) of the LED bulb? Answer to two decimal places, do not include unit symbols.
0.39 Energy = Power x duration. For example, 100W x 120h = 12,000Wh = 12 kWh, and 15W x 120h =1,800 Wh = 1.8 kWh Energy savings is the difference (12-1.8) kWh = 10.2 kWh; at the rate of 10 cents per kWh this amounts to $1.02
The stratosphere begins at what altitude?
10 miles Please refer to Lesson 4c: Introduction to Ozone / Good Ozone / Stratosphere.
An old refrigerator which is rated at 419 Watts and runs for 12 hours everyday is replaced by a new energy efficient refrigerator which is rated at 211 Watts and is expected to run 8 hours everyday. If electricity costs 9.7 cents (not $!) per kWh, what are the monetary savings ($) in the month of December?
10.05 Energy Consumed = (Wattage / 1000) x No. of hours per day x No. of daysElectricity cost = Energy Consumed x Cost per kWh
One food calorie is equal to how many calories?
1000
The Carnot efficiency of the automobile engine is 54%, and the flame temperature is 557 ℃, what is the exhaust temperature (℃)? Answer to two decimal places, do not include unit symbols.
108.72 Use the Carnot efficiency formula and temperatures in Kelvin.
A 144 watt electric warming blanket is operated for 9.9 hours per day during the winter, and winter lasts 104 days per year. At 0.08 dollars per kWh, what is the cost of the energy consumed by the electric blanket (dollars) each year? Answer to two decimal places, do not include unit symbols.
11.86 The electric blanket cost depends on the price and the consumed energy, and the consumed energy is derived from the power rate and working hours. For example, kWh x hr / day x day / y x $/kWh = $ / y.
Water heaters are typically set to _____degrees F.
120 degrees F
The useful output from a heat engine is 238 cal. The energy that is wasted is 4,084 J. What is the Carnot efficiency of the engine? (Answer with units of %. i.e. 30 not 0.3. you do not need to provide the %)
19.6 Efficiency = ((useful energy output) / (useful energy output + waste energy output))*100. Note: Use units consistently. Please refer the section of the Efficiency of Energy Conversion Devices.
Jane uses a water heater that is rated at 2,043 watts for 6 hours everyday. The cost of electricity in her region is 6.4 cents per kWh. Calculate the annual operating cost for the water heater in $.
286.35 Energy Consumed = (Wattage / 1000) x No. of hours per day x No. of daysElectricity cost = Energy Consumed x Cost per kWh
The country consumes 5 quadrillion BTUs of renewable energy and 10 quadrillion BTUs of nonrenewable energy every year. If the consumption of renewable energy is projected to increase at the rate of 19% per year for the next few decades, nonrenewable energy consumption remains constant. How many years does it take for renewable energy usage to reach the same amount of nonrenewable energy? Answer to two decimal places, do not include unit symbols.
3.68 Use doubling time formula
A room air conditioner used by Joel is rated at 404 watts. Joel used the air conditioner for 10 hours every week during summer. Calculate the total energy consumed by the air conditioner (in kWh) during the summer semester which runs for 10 weeks?
40.4 Energy Consumed = (Wattage / 1000) x No. of hours per day x No. of daysElectricity cost = Energy Consumed x Cost per kWh
16 million Joules of chemical energy are supplied to a boiler in a power plant. 8 x 106 Joules of energy are lost through unburnt fuel. The boiler radiates 1 million Joules to the atmosphere. What is the efficiency(%) of the boiler? (Your input answer should be in %, for example 50 not 0.5)
43.75 Energy efficiency = Useful energy output / Total energy input
If the energy input of a system is 104 calories and its output is 57 calories, what is the efficiency of the system? (Answer units: %, i.e. 30 not 0.3, do not include the %)
54.8 System Efficiency = (useful energy output) / (total energy input) * 100. Please refer to section: Efficiency of Energy Conversion Devices.
The flame temperature in an automobile engine is 958 °C, and the exhaust is emitted at 61 °C. What is the Carnot efficiency of the engine? (Answer units: %)
72.86 Use Carnot efficiency formula and temperatures in Kelvin. Please refer to section 3.7: The Carnot Efficiency
The flame temperature in an automobile engine is 2,059 °F, and the exhaust is emitted at 184 °F. What is the Carnot efficiency of the engine? (Answer with units of %. i.e. 30 not 0.3. you do not need to provide the %)
74.3 Use the Carnot efficiency formula and temperatures in Kelvin. Please refer to section covering The Carnot Efficiency
The coal consumption is observed to increase at the rate of 8% per year for a country. How long will it take to double the current usage of coal? (Please provide your answer to the nearest whole number)
9
The fastest growth in the energy use is projected for some of the ______ nations.
Asian
Which one of the following is a list of devices from least efficient to most efficient?
Automobile Engine, Power Plant, Electric Motor
Among the energy units listed, which one represents the most amount of energy?
Calorie (Food Calorie)
The television converts electricity to which of the following energy forms (select all that apply)
Correct! radiation energy Correct! mechanical energy Correct! thermal or heat energy
Which of the following is true about energy conversion devices?
Total Energy Input = Total Energy Output Total Energy Input = Useful Energy Output + Energy Dissipated to the surroundingsTotal Energy Input = Total Energy OutputEfficiency = Useful Energy Output / Total Energy Input
Which one of the following is NOT true about energy conversion devices?
Total Energy Input = Useful Energy Output Total energy = useful energy + waste energy. Refer to section 3.2: Energy Conversion Devices.
Without the greenhouse effect Earth would be a better place to live for humans.
False If there were no greenhouse gases in the atmosphere, the radiation received during the day time would be escaping in the night and the Earth would be at an average temperature (including summer, winter, night and day, and all latitudes) of 0�F. At this temperature, nothing grows on this planet and life cannot be supported.
Carbon monoxide is the only product when burning coal.
False In case there is not enough oxygen for complete oxidation, carbon monoxide (CO) may form. The carbon the fuel combines with the oxygen in the air used for burning and forms carbon dioxide. In case there is not enough oxygen for complete oxidation, carbon monoxide (CO) may form. Hydrogen (H) in the fuel oxidizes by combining with oxygen (O) and forms water (H2O). Please refer to Lesson 4a: Products of Combustion.
In the next 20 years, it is expected that renewable energy sources will supply more than half of the U.S. energy requirements.
False In the next 20 years renewables are expected to supply less than a third of the U.S. energy requirements.
Joule is a unit of power.
False Joule is a unit of energy used by scientists and engineers.
Doubling time is the time in which the rate of growth is doubled.
False The time it takes for the original (initial) quantity to double is called doubling time.
A turbine is the most efficient component in a power plant.
False Turbine, being a heat engine, is the least efficient component. Refer to section 3.8: Example of Power Plant Operation
Most of the energy demand in the US is met by renewable energy sources.
False We get most of our energy from nonrenewable energy sources, which include the fossil fuels: oil, natural gas, and coal.
Nuclear fission is renewable energy
False-Nuclear fission is nonrenewable energy because it uses nonrenewable material of uranium to generate power.
The U.S. has highest crude oil reserves in the world.
False-The United States ranks as eleventh in the world for reserves of oil. Please refer to section 2.5 Current and Future Energy Sources of the USA.
Which one of the following energy conversion devices has the highest energy efficiency?
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%.
Which of the following problems is caused by Sulfur Dioxide (SO2) emission, select all that apply.
Greenhouse effect Respiratory illness Sulfur dioxide (SO2) is a kind of greenhouse gas. Carbon monoxide (CO) may lead to poor learning ability. Long-term exposure to sulfur dioxide (SO2) results in the respiratory.
Which of the following action increase the power plant efficiency?
Hot temperature increase, cold temperature increase
Which one of the following causes global climate change?
Increase in the concentration of greenhouse gases in the atmosphere due to human activity It's well accepted by scientists that greenhouse gases trap heat in the Earth's atmosphere and tend to warm the planet. By increasing the levels of greenhouse gases in the atmosphere, human activities are strengthening Earth's natural greenhouse effect. The key greenhouse gases emitted by human activities remain in the atmosphere for periods ranging from decades to centuries.Lesson 4b: What is known for certain.
Placing your clothes dryer in a cold basement will make the dryer _____.
Less efficient Placing your clothes dryer in a cold basement will make the dryer _____.
At the present rate of consumption, how long are the U.S. petroleum reserves expected to last?
Less than 10 years At the current rate of consumption, the current U. S. petroleum reserves will last approximately for 2.2 years. Please refer to section 2.7: Lifetime of current reserves at constant consumption.
Which one of the following devices is least energy efficient if you consider its overall efficiency (i.e. efficiency costs of previous steps) ?
Light bulb The overall efficiency of end-use electrical appliances are quite low due to energy losses associated with generating electrical energy
Energy can be converted to which of the following?
Work Heat Radiation Correct! All of the above
You are at the most risk of lung damage due to smog if you are _____.
a young child Ozone may cause permanent lung damage. Repeated short-term ozone damage to children's developing lungs may lead to reduced lung function in adulthood. In adults, ozone exposure may accelerate the natural decline in lung function that occurs as part of the normal aging process. Please refer to Lesson 4c: Health and Environmental Impact / Below is a listing of Health Effects of Ground Level Ozone / Ozone may cause permanent lung damage.
Coal reserves for the World at the present rate of consumption will last for about ________.
about 150 years
Petroleum reserves for the World at the present rate of consumption will last for about _____.
about 50 years
In a heat engine, thermal energy is converted into _________ energy.
Mechanical
What is the form of useful energy output from a lawn mower?
Mechanical
What is the primary form of useful energy output in the case of a lawn mower?
Mechanical A lawn mower converts chemical energy from the burning of fuel into mechanical energy (rotation of blades). Refer to section 3.2: Energy Conversion Devices
Which of the following appliances has the lowest typical energy costs? (1 point)
Microwave oven Microwave operating costs less than 500 kWh/year, Dishwasher and washing machine operating costs 500-1000 kWh/year, and refrigerator operating costs more than 1000 kWh/year.
Bottom mounted refrigerators are _____ efficient compared to top mounted refrigerators
More
Refrigerators are heat _________.
Movers
In a heat engine what type of energy is converted to mechanical energy?
Thermal A heat engine is defined as a device that converts heat energy into mechanical energy. Refer to section 3.6: Heat Engines.
Which one of the following conditions contribute to acid rain damage?
areas with poor soil buffering capacity As this acidic water flows over and through the ground, it affects a variety of plants and animals. The strength of the effects depend on many factors, including:the acidity of the water;the chemistry and buffering capacity of the soils involved;the types of fish, trees, and other living things that rely on the water. Please refer to Lesson 4c: Acid Deposition.
What percentage of the U.S. energy demand is met by renewable energy sources?
around 10% About 10% of U.S. energy comes from renewable energy sources. Please refer to section 2.5: US Energy Consumption Over Time.
The time it takes for the initial quantity to become twice as much is called the _____.
doubling time
Which one of the following is true about global temperatures in the last century?
increased about 1 degrees C The increase in the greenhouse gases between 1950 and 2010 is believed to have caused an increase in the global temperature
"Resources" represent the portion of demonstrated energy resources that _____.
is known to exist or even suspected to exist, regardless of technical or economic viability
From the following, pick the set of units that contains all power or energy units.
kW, MW, BTU/s, J/s
Approximately what percentage of input electrical does an incandescent light bulb convert into visible light?
less than 10% Most of the electrical energy is lost in the form of heat in an incandescent light bulb. Refer to section 3.3: Energy Efficiencies.
Which of the following actions is not likely to improve the efficiency of a refrigerator?
switching the motor from a DC motor to a more efficient AC motor Switching the motor from a DC motor to a more efficient AC motor will not improve the efficiency of the refrigerator because DC motors are more efficient than AC motors.Checking the seals alone will not improve it will only identify the leak.Always freezers operate when loaded fully NOT overloaded.
What is the impact of methane and nitrous oxide on the atmosphere?
trap heat Methane and nitrous oxide trap heat like CO2 and are therefore classified as a greenhouse gases. The Global Warming Potential (GWP) of methane and N2O is about 25 and 298 respectively. Lesson 4b: Greenhouse Gases. Table: Change in greenhouse gas concentration between Pre-Industrial times and 2010.
On demand water heaters don't have large storage tanks.
true On-demand water heaters are in-line heaters and don't have a storage tank.
Geothermal heat can be used to produce electricity.
true Renewable and non renewable energy sources can be converted to electricity and heat.
What steps can lead to an energy efficient operation of a dishwasher?
wash only full loads use the no-heat air dry feature don't pre-rinse dishes before putting them in the dishwasher Correct! all of the above none of the above For energy-efficient operation of a dishwasher wash only full loads, use the no-heat air dry feature, and don't pre-rinse dishes before putting them in the dishwasher.
A conventional water heater consumes energy _____.
whether we use hot water or not Water heater consumes energy whether we use hot water or not. This is due to the heat lost to the surroundings.
If the atmosphere did not contain greenhouse gases, the planet would be hotter.
False CO2 and other greenhouse gases absorb part of the infrared radiation escaping earth's surface in the night. They therefore help keep the planet warmer. Please refer to Lesson 4b: Greenhouse effect.
The home oil furnace has a higher energy efficiency than the home gas furnace and home coal stove
False Home gas furnace energy efficiency is 95%, home oil furnace is 80%, and home coal stove is 75%
What is the term used to define the energy efficiency of a dishwasher?
EF Energy Factor (EF) is used to define energy efficiency of a dishwasher.
Which consumes the least amount of energy per day?
Eating your recommended amount of Calories
In a power plant, chemical energy is finally converted into_______energy.
Electrical
What kind of label do highly energy efficient appliances have? (1 point)
Energy Star label Highly Energy efficient appliances have an Energy Star label.
Two containers of oil are of different sizes but they have the same temperature, therefore they have the same energy content.
False
In the next 20 years, it is expected that renewable energy sources will supply more than half of the global energy requirements.
False In the next 20 years, it is expected that renewable energy sources will supply about 30% of global. energy requirements. Please refer to section Current and Future Energy Supply.
BTU/h is a unit of energy.
False A unit of energy equal to the amount of energy needed to raise the temperature of one pound of water by one degree Fahrenheit.
kWh is the unit of power.
False An amount of energy from the steady production or consumption of one kilowatt of power for a period of one hour
Most of the new electric power generation installations in the world are expected to be fossil fuel-based over the next two decades.
False As of 2020, 90 % of all new electric power generation additions are renewable in nature
Which energy source accounts for the greatest proportion of electricity generation in the US?
Natural Gas-In 2015, the share of electricity net generation provided by natural gas exceeded that of coal.
Which of these fuels represents the largest percent of the global energy supply?
Oil-Oil and coal are the the largest sources of energy in the world, but natural gas is quickly catching up.
According to estimation, which energy source is growing fastest between 2020 and 2050 for the U.S?
Other renewable energy Petroleum consumption increases by around 6 quadrillions BTU, natural gas increases by around 5 quadrillions BTU, Nuclear energy reduces by around 1 quadrillion BTU, and other renewable increases by around 10 quadrillions BTU
Which fuel supplies the greatest proportion of primary energy in the U.S.?
Petroleum-Petroleum accounts for almost 40% of the U.S.'s energy. Please refer to section 2.5: US Energy Consumption Over Time.
Which of the following is a form mechanical energy
Potential Energy
Joule per second is a unit of _________.
Power Joule is unit of energy used by scientists and engineers. J/s is the rate at which energy is used.
From a television, useful energy output is in the form of _____energy.
Radiant
What is the form of useful energy output in the case of a computer screen?
Radiation A computer screen converts electrical energy into radiation (the pictures and text that we see on the computer screen). Refer to section 3.2: Energy Conversion Devices.
Which of these energy sources is increasing its relative share of the global energy supply by the most since 2015?
Renewables
From the following, identify the group where all energy sources are renewable energy sources.
Solar, Nuclear Fusion Solar, Nuclear Fusion, Biomass, Wind, Tidal are renewable energy sources. Nuclear Fission, Petroleum, Coal are non-renewable energy sources.
If current trends persist, experts expect global temperatures to change by an addtional 1-5 degrees C by the year 2100.
True
The temperature of a substance is not a measure of its heat content, but a measure of the average kinetic energy of this molecules
True
Resources represent the portion of the energy that is known to exist or even suspected to exist, regardless of technical or economic viability
True Resources represent that portion of the energy that is known to exist or even suspected to exist, regardless of technical or economic viability. Please refer to section 2.7: Energy Reserves
Nuclear fusion is a renewable source of energy.
True - Nuclear fusion uses hydrogen isotopes and hydrogen isotopes can come from water. There is plenty of water on this planet to provide energy for literally millions of years. This makes nuclear fusion a renewable source of energy.
BTU is a unit of energy.
True A unit of energy equal to the amount of energy needed to raise the temperature of one pound of water by one degree Fahrenheit.
Energy and work have the same units.
True Energy is something that has ability to move things or do work.
Energy output must be equal to the input.
True First law of thermodynamics states that Energy output must be equal to the input.
Frost build up reduces the efficiency of freezers.
True Frost build-up in the freezer can reduce their efficiency.
Horizontal axis (front loading) washing machines are more efficient compared to agitation top loading models.
True Horizontal axis (front loading) washing machines are more efficient compared to top loading models.
Nitric oxide is a component of NOx.
True Nitrogen oxides, or NOx, is the generic term for a group of highly reactive gases, all of which contain nitrogen and oxygen in varying amounts. Please refer to Lesson 4a: Products of Combustion.
Solar radiation can be used to generate electricity.
True Renewable and non renewable energy sources can be converted to electricity and heat.
By 2050, renewable energy usage will exceed the sum of coal and natural gas in the fuel consumption for power generation in the world Correct!
True Renewable energy for power generation will be more than 200 quadrillions BTU, while the sum of coal and natural gas will reach around 165 quadrillions BTU.
The United States has about 1/4 of the world's coal deposits.
True The United States has 276,554 million ton of coal reserves and world has 997,748 million tons of coal. That means U.S. has 26.8% of world reserves.
A Calorie is a unit of energy
True The amount of energy needed to raise the temperature of one gram of water by one degree Celsius.
The atmospheric temperature and CO2 concentration changed prior to the pre-industrial periods.
True The ice core samples indicated that the atmospheric concentration of CO2 and temperatures fluctuated in the past significantly.
A BTU has more energy than a calorie
True, A BTU is the amount of heat required to heat 1 lb (454 grams) of water through 1°F. Whereas 1 calorie is the amount of heat required to raise 1 g of water through 1°C. Therefore there is more energy in one BTU
Energy can be converted from one form to another
True-Energy cannot be created or destroyed but it can be converted from one form to another.
