Reference no: EM13720822

Question 1: Good photovoltaic cells have an efficiency of approximately ________

 a) 2-6%

b) 28- 38%

c) 14- 17%

d) 38- 58%

Question 2: Hydroelectric power in the U.S. currently represents about ______ % of the total U.S. electricity.

a) less than 1

b) 40

c) 1

 d) 7

Question 3: A windmill system which produces 9 kW of electrical power when the wind is blowing at 4 m/s, will produce ______ kilowatts when the wind is blowing 8 m/s?

a) 72

b) 36

c) 24

d) 18

Question 4: Radioactivity refers to ________.

a) conversion of mass within the nucleus to energy

b) decay of nuclei induced with neutrons

c) the spontanious decay of atomic nuclei into lighter, more stable nuclei

d) decay of nuclei which must involve a neutrino or an antineutrino

Question 5: The Solar Constant, 2 calories per square centimeter per minute, is _______.

a) the average solar intensity at ground level

b) the annual amount of solar energy available at the top of the earth's atmosphere

c) the solar power density at 93 million miles from the sun

d) extremely variable

Question 6: In 2003 the wind energy generating capacity in the U.S. was about _______.

a) 6.4 GW

b) 6.4 MW

c) 6.4 kW

d) 6.4 TW

Question 7: The spectrum of solar radiation above the earth's atmosphere has its maximum in intensity _______.

a) at a wavelength higher than does the spectrum reaching the surface of the earth

b) at the same wavelength as does the spectrum reaching the surface of the earth

c) at a wavelength lower than does the spectrum reaching the surface of the earth

d) is not related to the maximum in the spectrum reaching the surface of the earth

Question 8: Your cottage foundation is made up of 800 cubic feet of concrete while the floor is made up of 200 cubic feet of oak. About how many Btu are required to raise the temperature of the foundation and floor by 30 degrees F? Given: 22 Btu per cubic feet per degree F for concrete and 25 Btu per cubic feet per degree F for wood.

a) 678,000

b) 150,000

c) 528,000

d) 1,500,000

Question 9: What is a thermal neutron?

a) a neutron with kinetic energy about 1/40 of an eV.

b) a neutron with a kinetic energy about 5 MeV

c) one of the neutrons which is produced in a typical nuclear fission reaction

d) a neutron inside any large nucleus

Question 10: Suppose you have a typical flat-plate solar collector with area 64 square feet. What is a reasonable number for the Btu per day collected as heat energy? Assume an efficiency of 50%.

a) 8,000

b) 64,000

c) 16,000

d) 32,000

Question 11  About _______ % of the total energy consumed in the U.S. each year is currently supplied by solar energy. Recall that we use about 98 QBtu per year.

a) 10

b) 6

c) 0.06

d) 1

Question 12  What is the base material and the doping material typically used in photovoltaic cells to convert solar radiation into electrical energy?

a) silicon doped with uranium

b) carbon doped with hydrogen

c) silicon doped with arsenic

d) antimony doped with silicon

Question 13: What is the typical size and voltage output of an individual solar cell?

a) 2 inches diameter and about 0.5 volt

b) 6 inches diameter and about 1 volt

c) 0.5 inch diameter and about 9 volts

d) 1 inch diameter and about 0.1 volts

Question 14: A parabolic reflector ________

a) focuses only the direct component of sunlight

b) focuses only the diffuse component of sunlight

c) focuses both the direct and diffuse components of sunlight

d) can be used for solare collection systems only if the overall efficiency is less than 5 %

Question 15: The temperature of the surface of the sun is about 5800 K. Using Stefan's law, find the power per unit area emitted by the sun assuming that the surface emissivity is ideal, i.e. epsilon=1.

a) 16 MW/square meter

b) 64 MW/square meter

c) 100 MW/square meter

d) 6.4 GW/square meter

Question 16: What is the pressure due to the water in pounds per square inch (psi) at the bottom of the static column of water 300 feet deep? Recall that pressure is density times acceleration due to gravity times the height---and be careful about the units.

a) 14.7 psi

b) psi 1470

c) 62.4 psi

d) 130 psi

Question 17 How much electric power could be obtained from a small hydroelectric station if the elevation change were 90 meters and if 12,000 kg of water passed through the turbines every second, with the overall efficiency being 80%?

a) 8.8 kW

b) 1.5 MW

c) 8.5 MW

d) 12.5 MW

Question 18:  The total mass energy of 200 grams of carbon is ________.

a) 18 QWh

b) 18 QCal

c) 18 QBtu ]

d) 18 QJ

Question 19: What is the purpose of a breeder reactor?

a) reduce the threat of nuclear weapons proliferation

b) reduce the thermal polution

c) to extend the useful lifetime of our uranium

d) reduce the amount of plutonium produced

Question: How much thermal energy in joules is made available by cooling 1 cubic meter of rock from 240 degrees C to 100 degrees C? The specific heat is 2.4 J per cubic centimeter per degree C.

a) 24.0 billion J

b) 33.6 billion J

c) 240 million J

d) 336 million J

Question 21: Which isotope of uranium is particularly good for fission with thermal neutrons?

a) uranium- 238

b) uranium- 236

c) uranium- 235

d) uranium- 233

Question 22: If the wind blows at a steady 10 m/s, the electric power generated in a particular windmill system is 200 W/square meter. How much energy could we get in a year per square meter through the use of this windmill?

a) 60 kWh

b) 500 kWh

c) 1000 kWh

d) 1750 kWh

Question 23: Ocean thermal gradient heat engines would have an ideal (Carnot) efficiency of about _______.

a) 7%

b) 17%

c) 25%

d) 1%

Question 24: Gasohol is a blend of corn-based ethanol plus gasoline. What is the typical ethanol content in the gasoline sold at service stations that do provide gasohol?  

a)1-6%

b) 6-12%

c) 12%

d)-15%-18%

Question 25: Tidal basins fill and empty on a regular schedule owing the orbit of the moon. About how many high tides are there each year?

a) 365

b) 700

c) 12

d) we can't predict that number

Question 26: Chemical energy available in such reactions as one would find in a hydrogen fuel cell is a few electron-volts. Nuclear fission reactions one would find in a nuclear power reactor release about how many times greater energy?

a) 10 million

b) 100 million

c) 1 billion

d) 100 billion

Question 27: In a typical fission of uranium, the number of neutrons emitted is about ________.

a) zero to 1

b) 2 to 3

c) 10 to 12

d) 235

Question 28: In a D-T fusion reaction, how many protons are involved?

a) 4

b) 3

c) 2

d) 1

Question 29: The net result of nuclear fusion processes within our sun which generate lifegiving energy is ________.

a) converting helium to either deuterium, tritium, or free protons and neutrons

b) taking four protons and converting 2 to neutrons in the process of fusing them into helium

c) converting all heavy elements to protons, because there's nothing more stable

d) taking two protons and two neutrons and fusing to form 2 deuterium.