What is the theoretical limit of the efficiency of a single-crystal single-junction cell in a photovoltaic system? w) 9 percent x) 29 percent y) 79 percent z) 99 percent

What is the theoretical limit of the efficiency of a single-crystal single-junction cell in a photovoltaic system? w) 9 percent x) 29 percent y) 79 percent z) 99 percent
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ANSWER: X -- 29 PERCENT
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A semiconductor device made up of a single p-n Junction is called a: w) transistor x) diode y) Fet z) integrated circuit

Description : A semiconductor device made up of a single p-n Junction is called a: w) transistor x) diode y) Fet z) integrated circuit

Last Answer : ANSWER: X -- DIODE

In quantum chemistry, a nodal surface: w) gives 99 percent contour surface for an orbital x) exists for a 1s orbital y) has quantum number l = 1 z) is an orbital surface on which the probability density is zero

Description : In quantum chemistry, a nodal surface: w) gives 99 percent contour surface for an orbital x) exists for a 1s orbital y) has quantum number l = 1 z) is an orbital surface on which the probability density is zero

Last Answer : ANSWER: Z -- IS AN ORBITAL SURFACE ON WHICH THE PROBABILITY DENSITY IS ZERO 

In a typical power plant used to generate electricity in the U.S., the percentage of energy in the fuel that is converted to electricity is about: w) 99 percent x) 50 percent y) 35 percent z) 10 percent

Description : In a typical power plant used to generate electricity in the U.S., the percentage of energy in the fuel that is converted to electricity is about: w) 99 percent x) 50 percent y) 35 percent z) 10 percent

Last Answer : ANSWER: Y -- 35 PERCENT 

How many atoms per unit cell are in a face-centered-cubic crystal? w) two x) four y) six z) eight

Description : How many atoms per unit cell are in a face-centered-cubic crystal? w) two x) four y) six z) eight

Last Answer : ANSWER: X -- FOUR

Planck's constant was first introduced in order to obtain a correct theoretical prediction of: w) the distribution of frequencies occurring in black body radiation. x) the energy produced by the transformation of mass into energy. y) the speed of light. z) lifetime of the neutron.

Description : Planck's constant was first introduced in order to obtain a correct theoretical prediction of: w) the distribution of frequencies occurring in black body radiation. x) the energy produced by the transformation of mass into energy. y) the speed of light. z) lifetime of the neutron.

Last Answer : ANSWER: W -- THE DISTRIBUTION OF FREQUENCIES OCCURRING IN BLACK BODY RADIATION

The speed of light through a single-mode optical fiber is approximately: w) c (equal to 3 x 108 m/s) x) 70 percent of c y) 80 percent of c z) 90 percent of c

Description : The speed of light through a single-mode optical fiber is approximately: w) c (equal to 3 x 108 m/s) x) 70 percent of c y) 80 percent of c z) 90 percent of c

Last Answer : ANSWER: X -- 70 PERCENT OF c

A ball falling vertically from rest for 3 seconds travels very nearly: w) 14.7 meters x) 29.4 meters y) 44.1 meters z) 88.2 meters

Description : A ball falling vertically from rest for 3 seconds travels very nearly: w) 14.7 meters x) 29.4 meters y) 44.1 meters z) 88.2 meters

Last Answer : ANSWER: Y -- 44.1 METERS

Quantity of fissionable material (i.e. U-235) in natural uranium is __________ percent. (A) 0.71 (B) 6.31 (C) 99.29 (D) 12.73

Description : Quantity of fissionable material (i.e. U-235) in natural uranium is __________ percent. (A) 0.71 (B) 6.31 (C) 99.29 (D) 12.73

Last Answer : (A) 0.71

Air/fuel ratio by weight for combustion of methane with theoretical quantity of air will be about (A) 9 : 1 (B) 17 : 1 (C) 23 : 1 (D) 29 : 1

Description : Air/fuel ratio by weight for combustion of methane with theoretical quantity of air will be about (A) 9 : 1 (B) 17 : 1 (C) 23 : 1 (D) 29 : 1

Last Answer : (B) 17 : 1

Which one of the following is the advantage of connecting two dry cells in parallel instead of in series? Is it because the parallel arrangement: w) gives twice the EMF of one dry cell x) has no internal resistance y) generates heat in an external circuit half as fast as would a single cell z) has half the internal resistance of a single cell

Description : Which one of the following is the advantage of connecting two dry cells in parallel instead of in series? Is it because the parallel arrangement: w) gives twice the EMF of one dry cell x) has no ... circuit half as fast as would a single cell z) has half the internal resistance of a single cell

Last Answer : ANSWER: Z -- HAS HALF THE INTERNAL RESISTANCE OF A SINGLE CELL 

Which of the following quantities has the GREATEST influence on the overall efficiency of a conventional (Rankine cycle) electric generating station burning fossil fuels? w) steam temperature at the steam turbine inlet x) net heating value of the fuel y) steam pressure at the steam turbine inlet z) pounds of ash and sulfur per pound of fuel

Description : Which of the following quantities has the GREATEST influence on the overall efficiency of a conventional (Rankine cycle) electric generating station burning fossil fuels? w) steam temperature at the steam turbine ... pressure at the steam turbine inlet z) pounds of ash and sulfur per pound of fuel 

Last Answer : ANSWER: W -- STEAM TEMPERATURE AT THE STEAM TURBINE INLET 

It takes 500 watts to operate a machine whose power output is 480 watts. Which of the following is the efficiency of the machine? Is it w) 20% x) 48% y) 96% z) 98%

Description : It takes 500 watts to operate a machine whose power output is 480 watts. Which of the following is the efficiency of the machine? Is it w) 20% x) 48% y) 96% z) 98%

Last Answer : ANSWER: Y -- 96%

A machine having an efficiency of 50% does 500 joules of work. Which of the following is the work input? Is it: w) 500 joules x) 250 joules y) 1000 joules z) 2500 joules

Description : A machine having an efficiency of 50% does 500 joules of work. Which of the following is the work input? Is it: w) 500 joules x) 250 joules y) 1000 joules z) 2500 joules

Last Answer : ANSWER: Y -- 1000 JOULES

A machine's output is 4000 joules and its frictional losses are 1000 joules. Which of the following is its efficiency? Is it: w) 25% x) 30% y) 75% z) 80%

Description : A machine's output is 4000 joules and its frictional losses are 1000 joules. Which of the following is its efficiency? Is it: w) 25% x) 30% y) 75% z) 80%

Last Answer : ANSWER: Z -- 80%

The thermal efficiency of an air/fuel gas preheating recuperator may be as high as __________ percent. (A) 50 (B) 65 (C) 85 (D) 99

Description : The thermal efficiency of an air/fuel gas preheating recuperator may be as high as __________ percent. (A) 50 (B) 65 (C) 85 (D) 99

Last Answer : (C) 85

The sun is containing ---- % mass of the solar system? A. 75.24% B. 79.36% C. 89.10% D. 99.86% (Answer)

Description : The sun is containing ---- % mass of the solar system? A. 75.24% B. 79.36% C. 89.10% D. 99.86% (Answer)

Last Answer : D. 99.86% (Answer)

Which one of the following is an example of chemical weathering? w) the splitting of a boulder x) the grinding of pebbles into sand y) the cleavage of a feldspar crystal z) the rusting of hornblende

Description : Which one of the following is an example of chemical weathering? w) the splitting of a boulder x) the grinding of pebbles into sand y) the cleavage of a feldspar crystal z) the rusting of hornblende

Last Answer : ANSWER: Z -- THE RUSTING OF HORNBLENDE

Which of the following terms means that a crystal has the ability to capture and hold water molecules? w) hydroponic x) hygroscopic y) hydrophobic z) hydropholectic

Description : Which of the following terms means that a crystal has the ability to capture and hold water molecules? w) hydroponic x) hygroscopic y) hydrophobic z) hydropholectic

Last Answer : ANSWER: X -- HYGROSCOPIC

Which one of the following is classified as a covalent network solid crystal? w) CaO x) SiO2 y) CO2 z) Pb

Description : Which one of the following is classified as a covalent network solid crystal? w) CaO x) SiO2 y) CO2 z) Pb

Last Answer : ANSWER: B -- SiO2

What is a typical spacing between atoms in a crystal, e.g., copper or rock salt? w) 0.1 Angstroms x) 2 Angstroms y) 20 Angstroms z) 100 Angstroms

Description : What is a typical spacing between atoms in a crystal, e.g., copper or rock salt? w) 0.1 Angstroms x) 2 Angstroms y) 20 Angstroms z) 100 Angstroms

Last Answer : ANSWER: B -- 2 ANGSTROMS

Which class of solids could have London Forces the attractive forces between particles in crystal lattice positions? w) ionic x) covalent y) metallic z) molecular

Description : Which class of solids could have London Forces the attractive forces between particles in crystal lattice positions? w) ionic x) covalent y) metallic z) molecular

Last Answer : ANSWER: Z -- MOLECULAR

A crystallized substance containing water of crystallization is most appropriately termed: w) a hydrate x) an oxide y) a hydroxide z) a condensation crystal

Description : A crystallized substance containing water of crystallization is most appropriately termed: w) a hydrate x) an oxide y) a hydroxide z) a condensation crystal

Last Answer : ANSWER: W -- A HYDRATE

The type of crystal lattice exemplified in a diamo is: w) ionic crystal x) covalent network crystal y) metallic crystal z) covalent molecular crystal

Description : The type of crystal lattice exemplified in a diamo is: w) ionic crystal x) covalent network crystal y) metallic crystal z) covalent molecular crystal

Last Answer : ANSWER: X -- COVALENT NETWORK CRYSTAL

Solids may be considered to be either crystalline noncrystalline. The basic difference between them is that a crystal, in contrast to a noncrystal: w) has a sharp melting point x) has an irregular array of atoms y) exhibits double refraction z) has a completely regular atomic or molecular structure

Description : Solids may be considered to be either crystalline noncrystalline. The basic difference between them is that a crystal, in contrast to a noncrystal: w) has a sharp melting point x) has an irregular array of atoms y) exhibits double refraction z) has a completely regular atomic or molecular structure

Last Answer : ANSWER: Z -- HAS A COMPLETELY REGULAR ATOMIC OR MOLECULAR STRUCTURE

The energy dissipated when a car hits a tree at 70 miles per hour is ABOUT how much greater than that dissipated at 50 miles per hour? w) 20 percent x) 40 percent y) 70 percent z) 100 percent

Description : The energy dissipated when a car hits a tree at 70 miles per hour is ABOUT how much greater than that dissipated at 50 miles per hour? w) 20 percent x) 40 percent y) 70 percent z) 100 percent

Last Answer : ANSWER: Z -- 100 PERCENT

If a 99.79 kg man jumps from the top of a 176.8 meter tall building how long does it take for his body to decelerate to 0 ms once first contact with the ground is made?

Description : If a 99.79 kg man jumps from the top of a 176.8 meter tall building how long does it take for his body to decelerate to 0 ms once first contact with the ground is made?

Last Answer : It depends upon how much the ground deforms once the first bit of his body hits the ground, and how much his body deforms once the first bit of his body has hit the ground. The former is likely to be ... his body). It will be any time greater than 0 seconds, the the amount of time depends as above.

The device used to convert solar energy into electricity is – (1) Photovoltaic cell (2) Daniell cell (3) Electrochemical cell (4) Galvanic cell

Description : The device used to convert solar energy into electricity is – (1) Photovoltaic cell (2) Daniell cell (3) Electrochemical cell (4) Galvanic cell

Last Answer : (1) Photovoltaic cell Explanation: Sunlight is converted into electricity using photovoltaics (PV). A photovoltaic system employs solar panels composed of a number of solar cells to supply usable solar power.

The device used to convert solar energy into electricity is (1) Photovoltaic cell (2) Daniell cell (3) Electrochemical cell (4) Galvanic cell

Description : The device used to convert solar energy into electricity is (1) Photovoltaic cell (2) Daniell cell (3) Electrochemical cell (4) Galvanic cell

Last Answer : Photovoltaic cell

The maximum percentage of CO2 in a flue gas (from a carbonaceous fuel) can be(A) 21(B) 77(C) 79(D) 29

Description : The maximum percentage of CO2 in a flue gas (from a carbonaceous fuel) can be (A) 21 (B) 77 (C) 79 (D) 29

Last Answer : (A) 21

A national random sample of 20 ACT scores from 2010 is listed below. Calculate the sample mean and standard deviation. 29, 26, 13, 23, 23, 25, 17, 22, 17, 19, 12, 26, 30, 30, 18, 14, 12, 26, 17, 18 a. 20.50, 5.79 b. 20.50, 5.94 c. 20.85, 5.79 d. 20.85, 5.94

Description : A national random sample of 20 ACT scores from 2010 is listed below. Calculate the sample mean and standard deviation. 29, 26, 13, 23, 23, 25, 17, 22, 17, 19, 12, 26, 30, 30, 18, 14, 12, 26, 17, 18 a. 20.50, 5.79 b. 20.50, 5.94 c. 20.85, 5.79 d. 20.85, 5.94

Last Answer : Katie earned 84,92,84,75 and 70 on her first 5 tests. What is the minimum grade Katie needs to earn on the next test to have a mean of 84?

When white light is passed through a double slit which of the following statements is TRUE: w) Each of the bright bands is dispersed into a spectrum x) Only the central band is dispersed into a spectrum y) All the bright bands except the central one are dispersed into a spectrum z) Each band has a single color different from its neighboring bands

Description : When white light is passed through a double slit which of the following statements is TRUE: w) Each of the bright bands is dispersed into a spectrum x) Only the central band is dispersed into ... one are dispersed into a spectrum z) Each band has a single color different from its neighboring bands 

Last Answer : ANSWER: Y -- ALL THE BRIGHT BANDS EXCEPT THE CENTRAL ONE ARE DISPERSED INTO THE SPECTRUM

A virtual image can be formed by one or more of the following single mirrors? Identify them. w) plane mirror x) concave spherical mirror y) convex spherical mirror z) all of the above

Description : A virtual image can be formed by one or more of the following single mirrors? Identify them. w) plane mirror x) concave spherical mirror y) convex spherical mirror z) all of the above

Last Answer : ANSWER: Z -- ALL OF THE ABOVE (accept: A, B and C) 

An object dropped from rest near the Earth's surface will fall how far in the first second: w) 4.9 meters x) 9.8 meters y) 16.0 meters z) 32 metersAn object dropped from rest near the Earth's surface will fall how far in the first second: w) 4.9 meters x) 9.8 meters y) 16.0 meters z) 32 meters

Description : An object dropped from rest near the Earth's surface will fall how far in the first second: w) 4.9 meters x) 9.8 meters y) 16.0 meters z) 32 meters

Last Answer : ANSWER: W -- 4.9 METERS

What is the DeBroglie wavelength of a 1,200 kilogram corvette traveling at a rate of 25 meters per second? Planck's constant is equal to 6.62 x 10-34 Joule-seconds. w) 5.3 x 10-32 meters x) 5.9 x 10-34 meters y) 2.1 x 10-38 meters z) 1.6 x 10-40 meters

Description : What is the DeBroglie wavelength of a 1,200 kilogram corvette traveling at a rate of 25 meters per second? Planck's constant is equal to 6.62 x 10-34 Joule-seconds. w) 5.3 x 10-32 meters x) 5.9 x 10-34 meters y) 2.1 x 10-38 meters z) 1.6 x 10-40 meters

Last Answer : ANSWER: Y -- 2.1 x 10-38 METERS

A typical microwave oven produces microwave radiation with a wavelength of: w) 3 meters x) 3 x 10-2 meters (read: 3 times 10 to the minus 2 meters) y) 3 x 10 -6 meters (read: 3 times 10 to the minus 6 meters) z) 3 x 10-9 meters (read: 3 times 10 to the minus 9 meters)

Description : A typical microwave oven produces microwave radiation with a wavelength of: w) 3 meters x) 3 x 10-2 meters (read: 3 times 10 to the minus 2 meters) y) 3 x 10 -6 meters (read: 3 times 10 to the minus 6 meters) z) 3 x 10-9 meters (read: 3 times 10 to the minus 9 meters) 

Last Answer : ANSWER: X -- 3 x 10-2 METERS

A bullet is fired with a muzzle velocity of 1000 meters per second from a rifle clamped to a window 4.9 meters above ground level. Neglecting air resistance, the horizontal distance from the rifle at which the bullet will strike the ground is w) 4.9 meters x) 500 meters y) 1000 meters z) 4900 meters

Description : A bullet is fired with a muzzle velocity of 1000 meters per second from a rifle clamped to a window 4.9 meters above ground level. Neglecting air resistance, the horizontal distance from the rifle at which the bullet will strike the ground is w) 4.9 meters x) 500 meters y) 1000 meters z) 4900 meters

Last Answer : ANSWER: Y -- 1000 METERS

An object is projected vertically upward near the surface of the earth. At the very top of its path, the object's velocity is zero, and its acceleration is: w) 0 x) 9.8 meters per second squared DOWNWARD y) 9.8 meters per second squared UPWARD z) depends on the mass of the object

Description : An object is projected vertically upward near the surface of the earth. At the very top of its path, the object's velocity is zero, and its acceleration is: w) 0 x) 9.8 meters per second squared DOWNWARD y) 9.8 meters per second squared UPWARD z) depends on the mass of the object

Last Answer : ANSWER: X -- 9.8 METERS PER SECOND SQUARED DOWNWARD

One nanometer is equal to: w) 10-12 meters x) 10-11 meters y) 10-3 meters z) 10-9 meters

Description : One nanometer is equal to: w) 10-12 meters x) 10-11 meters y) 10-3 meters z) 10-9 meters

Last Answer : ANSWER: Z -- 10-9 METERS 

A child weighing 50 Newtons is on a swing. He goes from a minimum height of 0.2 meters to a maximum height of 1.5 meters. His maximum speed is closest to: w) 3 meters per second x) 5 meters per second y) 7 meters per second z) 9 meters per second

Description : A child weighing 50 Newtons is on a swing. He goes from a minimum height of 0.2 meters to a maximum height of 1.5 meters. His maximum speed is closest to: w) 3 meters per second x) 5 meters per second y) 7 meters per second z) 9 meters per second

Last Answer : ANSWER: X -- 5 METERS PER SECOND

When a beam of ordinary white light is passed through a Polaroid plate filter, the intensity of the beam that emerges is: w) equal to that of the incident beam x) about 0.9 that of the incident beam y) about one-half that of the incident beam z) practically zero

Description : When a beam of ordinary white light is passed through a Polaroid plate filter, the intensity of the beam that emerges is: w) equal to that of the incident beam x) about 0.9 that of the incident beam y) about one-half that of the incident beam z) practically zero

Last Answer : ANSWER: Y -- ABOUT ONE-HALF THAT OF THE INCIDENT BEAM 

A girl throws a 0.1 kilogram ball at a wall. The ball hits the wall perpendicularly with a velocity of 5 meters per second and then bounces straight back with a velocity of 4 meters per second. The change in the momentum of the ball is: w) 0.1 kilogram-meters per second x) 0.4 kilogram-meters per second y) 0.5 kilogram-meters per second z) 0.9 kilogram-meters per second

Description : A girl throws a 0.1 kilogram ball at a wall. The ball hits the wall perpendicularly with a velocity of 5 meters per second and then bounces straight back with a velocity of 4 meters per second. The ... .4 kilogram-meters per second y) 0.5 kilogram-meters per second z) 0.9 kilogram-meters per second

Last Answer : ANSWER: Z -- 0.9 KILOGRAM-METERS PER SECOND 

If the distance between two objects, each of mass 'M', is tripled, the force of attraction between the two objects is: w) 1/2 the original force x) 1/3 the original force y) 1/9 the original force z) unchanged

Description : If the distance between two objects, each of mass 'M', is tripled, the force of attraction between the two objects is: w) 1/2 the original force x) 1/3 the original force y) 1/9 the original force z) unchanged

Last Answer : ANSWER: Y -- 1/9 THE ORIGINAL FORCE 

Two forces have magnitudes of 11 newtons and 5 newtons. The magnitude of their sum could NOT be equal to which of the following values? w) 16 newtons x) 5 newtons y) 9 newtons z) 7 newtons

Description : Two forces have magnitudes of 11 newtons and 5 newtons. The magnitude of their sum could NOT be equal to which of the following values? w) 16 newtons x) 5 newtons y) 9 newtons z) 7 newtons 

Last Answer : ANSWER: X -- 5 NEWTONS

The sun makes up approximately what percent of matter in our solar system? w) 17% x) 50% y) 85% z) 99%

Description : The sun makes up approximately what percent of matter in our solar system? w) 17% x) 50% y) 85% z) 99% 

Last Answer : ANSWER: Z -- 99% 

A pair of rivers that mark the approximate southern limit of the Ice Age glaciers in North America are the Missouri and which of the following? w) St. Lawrence x) Ohio y) Delaware z) Tennessee

Description : A pair of rivers that mark the approximate southern limit of the Ice Age glaciers in North America are the Missouri and which of the following? w) St. Lawrence x) Ohio y) Delaware z) Tennessee

Last Answer : ANSWER: X -- OHIO

Consider efficiencies of hydro-turbines and generators. If the efficiency of a hydro-turbine is 80% and the efficiency of a generator is 90%, what is the overall efficiency of the unit? w) 85% x) 72% y) 90% z) 70%

Description : Consider efficiencies of hydro-turbines and generators. If the efficiency of a hydro-turbine is 80% and the efficiency of a generator is 90%, what is the overall efficiency of the unit? w) 85% x) 72% y) 90% z) 70% 

Last Answer : ANSWER: X -- 72%

Percentage of U-238 in natural uranium is around (A) 0.71 (B) 99.29 (C) 0.015 (D) 29.71

Description : Percentage of U-238 in natural uranium is around (A) 0.71 (B) 99.29 (C) 0.015 (D) 29.71

Last Answer : (B) 99.29

The continental shelves comprise what percentage o the Earth's total land area? w) 38 percent x) 28 percent y) 18 percent z) 8 percent

Description : The continental shelves comprise what percentage o the Earth's total land area? w) 38 percent x) 28 percent y) 18 percent z) 8 percent

Last Answer : ANSWER: Y -- 18 PERCENT

Of the energy used in the United States, about wha percent is provided by hydroelectric power? w) 4% x) 20% y) 50% z) 75%

Description : Of the energy used in the United States, about wha percent is provided by hydroelectric power? w) 4% x) 20% y) 50% z) 75%

Last Answer : ANSWER: W -- 4%

Which of the following is the element which makes up about 8 percent of the earth's crust and occurs in all rocks except limestone and sandstone? w) sulfur x) aluminum y) sodium z) magnesium

Description : Which of the following is the element which makes up about 8 percent of the earth's crust and occurs in all rocks except limestone and sandstone? w) sulfur x) aluminum y) sodium z) magnesium

Last Answer : ANSWER: X -- ALUMINUM