PSC101 Exam 3
Infrared radiation is also called IR. Describe how it is different from visible light. What emits IR? Can animals use it? Explain how emission of IR sometimes "wastes" energy. Give examples showing how IR is used in modern technology.
Infrared light has a lower frequency compared to visible light where the energy per photon of visible light is more than that of IR light. Warm objects emit IR. Some animals can use it to see for night vision such as cats or bats. The emission of IR wastes energy which can be explained using the greenhouse effect. IR is used in modern technology to detect heat differences in objects or to keep things warm.
which color of star would be the hottest
blue
The least expensive form of carbon abatement (putting less CO2 into the atmosphere) is
conservation
To be affordable without subsidy or carbon credits, the cost of a billion-watt solar plant must be not much more than
$1 billion
Describe the key features of quantum physics that make it different from "ordinary" physics. Give examples showing how these features are used in important applications.
- Quantization of energy- Ordinary physics would predict that the energy can be supplied continuously to a particle while quantum mechanics predicts that energy is absorbed & emitted one stroke in form of packets of quantum. Used in spectral fingerprinting to identify an element. - Uncertainty principle - A particle can simultaneously be present at several physical locations. "Ordinary" physics suggests that one can measure both momentum & position simultaneously & that a particle can be present at one single location only at a given time. - Quantum tunneling- refers to crossing of energy levels by particles which are otherwise forbidden by energy conservation law. Allows for the particle to tunnel through the barrier if it has a lower energy. This is not seen in classical physics. This concept is used in scanning tunneling microscope in which a needle scans the complete surface of a metal. - Wave-particle duality - in ordinary physics something is either a wave or a particle. In quantum mechanics light is said to have a dual nature. It behaves as a particle as well as a wave. Photoelectric effect makes use of dual nature of light. Used in solar cells, digital camera, xerox machines. -Wavefunction collapse hypothesis is a distinct feature of quantum mechanics. It states that any system stays as a superposition of all possible state that it can attain. Only when a measurement is made, its wave function collapses to one of the states. In ordinary physics, it is supposed that if one can observe particle in a particular state, it stays in the same state even while observation is not being carried out. No direct practical application of wave function collapse theory, its used to understand the state of existence of anything in quantum mechanics.
UV light
- is responsible for sunburns and windburns - is used to kill bacteria in the water of remote villages in India -is also called black light
What are the various possible solutions to the CO2 problem? List them, and give the pros and cons for each. Which are most readily adoptable by developing countries?
-Energy Efficiency & Conservation - using less energy for doing the same work. By using appropriate roofing material that reflects most of the sunlight, the heating of the home is considerably reduced which lowers the energy required for air conditioning. - Clean Coal - refers to the use of coal where the created CO2 is not allowed to escape into the atmosphere, rather it is captured & stored properly. - Biomass this a direct burn of wood, and peat, for cooking heat, it is widely used in developing countries. This method has a positive impact on the world climatic change as it leads to a reduction of oil production as it is the renewable source of energy. Though a natural source of energy, it also bears some disadvantages such as land utilization, intensive in energy production and can lead to deforestation - Wind power is where the wind is intensively used to run turbines and in return produces energy; this leads to the reduction in carbon emitted in space. Some of the advantages include clean energy; no fuel to drilling or for transport and it is also renewable. On the look it bears some cons such as being an expensive source, this makes it to mostly use by developed countries. - Solar heating and cooling are the most basic form of energy utilization commonly known as solar heating, domestically is used to dry cereals and clothes, this type of energy is mostly used in developing countries since it is a ready energy and always available. However, it is an intermitted and cheap power source'. Energy Efficiency & Conservation is the easiest & least expensive way to reduce the green house emissions & hence it will be particular useful for the developing countries.
Describe phenomena that depend on the presence of an energy gap.
-Superconductivity - electrons behave as waves & can interfere with each other while moving in a crystal. This gives rise to allowed & impossible energy levels for electrons in crystals. There exist gaps between allowed energy levels. - Lasers - light emission by lasers is a stimulated process, which involves a quantum chain reaction where a photon stimulates light emission by transit of an electron from a higher energy level to a lower energy level in atoms in excited state. - fluorescence or phosphorescence depending on the material. Some objects glow in the dark, which can absorb photons when exposed to light in which excite electrons to higher energy levels. When the electrons return to lower energy levels, light is emitted.
the photon has a rest mass approximately equal to
0
when the velocity of a proton is half of the speed of light, then the gamma function is approximately equal to
1
if one person travels at 99% the speed of light for 7 years, how much younger will he be than his identical twin who didn't travel?
1 year
if you travel at 50% of the speed of light, your mass is increased by a factor
1.15
The Age of the Universe is closest to
10 billion years
Cooling in the last big ice age, which ended about 12,000 BC, was approximately
11 degrees F
if the velocity is (12/13)c, then the gamma function is
13/5
High-temperature superconductors operate at approximately
150 K (liquid nitrogen)
A tungsten lightbulb has 100 watts printed on it.About how much power is actually emitted as visible light
16 watts
Which of these years had the warmest worldwide climate?
1998
Higher carbon dioxide levels than we have now were last seen about
20 million years ago (no option)
a neutrino can have which of the following values for its energy?
200 joules
If the United States reduced CO2 emissions to those suggested by the Kyoto treaty, and the developing nations continued to increase theirs at the current (allowed) rate, then global warming would be delayed by about
3 years
A radioactive particle has a half-life of 1 second. If it moves at 3/5 the speed of light, its new half-life will be
5/4 seconds
Which of the following is a typical energy for an x=ray?
50,000 eV
The average temperature of the Earth (including the poles and the equator) is now about
57 degrees F
In France, nuclear power produces what percentage of the electricity?
80%
Which of the following has the lowest frequency?
AM radio
Energy can be converted to mass, and mass to energy. Describe how. Give specific examples.
According to special theory of relativity, mass can be converted to energy & energy can be converted to mass. For example, in the process of pair production, the gamma ray as energy with zero mass can be converted to mass as positron & electron. In annihilation, the positron & electron annihilation can produce gamma ray as energy.
What phenomena can be understood as a consequence of tunneling? What practical applications are there to this behavior?
Alpha radioactivity may be understood as a consequence of tunneling. An alpha particle, which is a doubly charge helium nucleus is released from the nucleus of a radioactive substance. Calculations show that alpha particle ordinarily does not have the requisite energy to be emitted out of the nucleus. The concept of tunneling is used in scanning tunneling microscope in which a needle scans the complete surface of a metal. Electrons from needle flow as a current from needle to the surface & give information about the surface.
Converting coal to oil is achieved with A. pebble bed reactors B. Fisher-Tropsch C. enhanced oil recovery D. CIGS
B. Fisher-Tropsch
Discuss the military uses of invisible light.
Binoculars are used in the border areas. These binoculars are designed that they are sensitive to infrared radiation & can form the image of the person even when its dark.
Ozone depletion is caused by
CFC's
Which of the following is not a major greenhouse gas?
CFCs (such as Freon)
Which country produces the most greenhouse gas emission per GDP (gross domestic product)?
China
Humans have been polluting the atmosphere in ways that could have lasting effects for future generations. What are the chemicals that have been put into the air that could do this? What effects could they have? Describe as much of the relevant physics as you can.
Chlorofluorocarbons contain the element chlorine & fluorine which is highly stable, but at high atmosphere is hit by UV light & breaks into chlorine & fluorine atoms. Chlorine is very effective in turning ozone back to ordinary oxygen, in which destroys the ozone layer.
Describe what is meant by comfortable conservation. What other type of conservation could there be? Give several specific examples of each kind.
Comfortable conservation means conserving energy without sacrificing comfort - use insulation on walls & seal windows, doors, & air ducts - use efficient heating systems - use fluorescent bulbs for lighting. They use less energy, generate less heat, & last longer - switch off light, fan, & other electrical appliances when not needed Other type of conservations could be use of higher energy efficiency devices & processes - use of biofuel made from sugarcane & tall grass - nuclear power - wind energy - solar thermal
Many people use the terms greenhouse effect and ozone layer interchangeably as though they address the same issue. Explain the differences. Why are the greenhouse effect and ozone layer "controversial" in public debate? Describe the current day concerns for each, and what action is appropriate.
Damage to the ozone layer takes place due to gases such as CFC. The atmospheric ozone layer plays a major role in obstructing the dangerous ultraviolet radiations emitted from the Sun in reaching the Earth. The ozone layer saves us from the harmful effects of UV light of Sun. The greenhouse effect is the warming of Earth's atmosphere. The greenhouse gases, CO2 & methane, act like a blanket & prevent the head radiations of Earth from going into the space. This results in the gradual increase in the temperature of the Earth, leading to global warming. Depletion of ozone layer is not responsible for the greenhouse effect. The easiest & economically suitable option to solve the problem of greenhouse warming is to use the energy efficiency & conservation. To protect the ozone layer, phase out the use of CFCs & ultimately stop its use. We should also plant more trees so that more oxygen is produced which will eventually increase the ozone in the atmosphere.
Who is famous for his estimate of extraterrestrial intelligence?
Drake
Discuss Drake's equation. How is it used to argue that there must be intelligent life outside of the Earth? What are the weaknesses of this argument?
Drake's equation takes into account the number of civilizations as a mathematical product of the average rate of star formation and predicts possible planets which could sustain life. The Fermi Paradox states that there are many stars in the universe which are like our sun, there is a high probability of one of those suns having an earth like planet which might develop civilizations, those civilizations might develop interstellar travel and could travel across the milky way in a million years. This helps inform our use of Drakes Equation by letting us know that it is highly probable that there is extraterrestrial life out there.
the most accurate equation for energy is
E=mc^2
Visible light is an electromagnetic wave. Name five other phenomena that are also electromagnetic waves but have different names. (Try to pick things that a nonphysics student would not know were "light.") How do these waves differ? Briefly describe applications for each of these waves.
Gamma rays have very high frequency & they are highly energetic. The infrared waves have greater wavelength than gamma rays. The wavelength range is from 700nm to 100mm. In total darkness, you can see if you have a camera that is sensitive to infrared radiation. The microwaves have greater wavelength than infrared rays, the wavelength range is from 1mm to 1m. The range of the ultraviolet wave is from 10nm to 380nm. This creates the ozone in Earth's stratosphere in the process of striking of oxygen molecules. The wavelength of the x-ray is of the order of 1 x 10^-10 m. The x-ray images are shadows of semi-transparent objects. X-rays are absorbed by heavy elements rather than light elements.
Describe the greenhouse effect. What causes it? How big is it? What role does it play in global warming? How can the greenhouse effect be strengthened?
Greenhouse effect is due to the presence of excess quantity of greenhouse gases like CO2 in the atmosphere due to the burning of coal, oil & natural gas. Due to the increase in burning of fossil fuels, the percentage of CO2 in the atmosphere has increased from about 289 parts per million before the industrial revolution to over 360 parts per million at present. Adding a gas to the atmosphere strengthens the greenhouse effect that absorbs IR. Then less IR will leak out & more IR will be radiated back to the surface of the Earth, as a result the surface of the Earth will get warmer.
What is Hubble's law? Why do some people think that it means that we must be at the center of the Universe? Are they right? If not, explain the fault in their reasoning. If they are right, explain why we are at the center.
Hubble's law is the observation that the Universe is expanding uniformly. There is no center. The beginning was about 14 billion years ago, the Big Bang. No matter which galaxy they're sitting on, all other galaxies will appear to be receding from them.
What "evidence" for global warming is not really scientific evidence but only an example of either cherry-picking or exaggeration?
Hurricane Katrina is generally attributed to global warming thus, it is not really scientific evidence. It is claimed that both the number & intensity of hurricanes due to global warming has increased in recent decades, however, according to the IPCC, the number of hurricanes has not been increasing.
The organization that studies climate change is
IPCC
Bats navigate in caves by using
IR
Heat Radiation is also called
IR
Remote control of a TV is usually done using
IR
The greenhouse effect involves atmospheric emission of
IR
Pit vipers and mosquitoes can sense
IR radiation
Lasers are one of the most widely used technological inventions of the twentieth and twenty-first centuries. What does the word laser stand for? What properties of laser light make it useful? What are the main parts of a laser? What principles of quantum physics make a laser work? Give examples of devices that use lasers in your answer.
It stands for Light Amplification by Stimulated Emission of Radiation It it useful because the light from a laser only has one wavelength, making it so that its origin is only from one set of energy levels. You can also see different absorption and emissions . They are made of an energy source, two or more mirrors, and a medium. The process of stimulating photons is one main principle A laser pointer is one device, the properties of a laser allow a person to point out more specific things on a board than a flash light would. Wielding can be done with lasers because the metal is put through a concentrated heat source which is the beam. Eye surgery is done with lasers because it allows doctors to cut very precisely.
Jim and Mary are both from Berkeley and are the exact same age. Jim travels at a velocity of 65 miles per hour to Los Angeles and waits there. Mary drives the next day 70 mph. when she gets to Los Angeles, who is older?
Jim
A treaty that was signed by the United States but not ratified by the Senate is
Kyoto
What does it mean when we say that astronomical observations "look back in time"? Can we really see the past? Can we use this technique to see our own past?
Light travels with a constant speed through any medium. It takes time fro the light to travel in the Universe because the distance is greater. So when we see the light from very distant galaxies in the Universe, we are actually seeing the light emitted from that galaxy a long time ago. Distance between galaxies in the Universe is measured in light year. Light is a fossil record of the Universe after its birth. The observation of very distant galaxies is equal to looking backwards in time. Though the same technique cannot be used to see our past. Our past remains only in our memory.
The name NMR has been changed to
MRI
To image the hydrogen in the body use
MRI
the effects of special relativity must be take into account for
MRI
to image hydrogen in the brain, the best technique is
MRI
Many people worry that we are about to run out of oil. Is that true? Describe the relationship between available oil and its price. Could coal be used to replace oil?
No that is not true there are huge amounts of oil reserves through out many countries, especially in the united states. Oil prices are controlled by OPEC,and a lot of pricing depends on different countries, their taxes,and their relationship with countries they are buying oil from. The accessibility of oil, I think, doesn't effect the price the price as much as you would think. if it comes down to it coal could replace oil if it needed to happen.
Which of the following uses antimatter
PET scan
Modern medical imaging can do much more than take a simple x-ray. Define and explain four methods that are used for medical imaging. Explain the physics behind the techniques, describe what they measure, and say something about the applications.
PET scans use antimatter for scanning. A material is prepared containing the positron emitter. Used to check for diseases in the body. MRI - to image the hydrogen in the body, which maps the hydrogen distribution. CAT scans - are made by taking x-rays from many different directions. Sometimes the x-ray dose may be large which can cause cancer. Thermography - different objects radiate different wavelengths of infrared radiation with different intensities. The map of this emission gives the information regarding the temperature of the skin.
Many people think that quantum physics is used only in the laboratory. In fact, many devices that depend on quantum physics for their operation are used in business, industry, and our everyday lives. Give examples of four such uses, and for each one, describe how quantum physics is essential for its operation. Try to pick four devices that appear, to the nonphysics student, to be as different from each other as possible.
Quantum mechanics is applied in several devices that we find use in daily lives -Lasers work on the principal of quantum chain reaction. Light is emitted when an electron transits from a higher energy level to a lower one. Supermarket bar code reader uses a laser with a detector to read bar codes on different items. The laser in the bar code reader is moved rapidly so as to scan the whole of the bar code. The reflected light is analyzed with the help of a detector to read the price encoded in the bar code. - compact disks (CDs) also make use of lasers. It has music recorded on a thin layer of aluminum buried inside the plastic. - Solar cells are used to produce electricity using solar light. They consist of plates made of semiconductors, when light falls on these plates, electrons are emitted as a result of photoelectric effect. - x-rays are photons produced using electrons. X-ray machines look at deformities in structure of bones. They are produced when accelerated electrons are made to collide with metals. The energy carried by electrons is converted to a photon & emitted.
The country that produces the most carbon dioxide per person every year is
Saudi Arabia
What methods can be used to identify gases— for example, to tell whether a gas is hydrogen or helium or a mixture? Describe the principles on which the method is based.
Spectral finger printing may be used to distinguish between 2 gases. Spectrum analysis of the light from hot gas provides information about the frequencies present in the light. Because the nucleus has different charge for different elements, the electrons have different energy levels for each element. Hydrogen has 1 proton while helium has 2, the electron in helium has to move at a higher speed to balance the attraction & is at a higher energy level. Each different frequency corresponds to a difference in color, so it becomes easy to analyze the spectrum of each element. If the colors present in the spectrum correspond to energy levels of hydrogen, only hydrogen is present. For helium the corresponding pattern will be obtained. If a missed pattern is obtained it may be interfered that both gases are present.
Superconductivity sounds super, yet people do not use it in everyday life. Explain the nature of superconductivity, the physics behind it, and why it is not more widely used. Discuss its present-day applications, and the possibilities for the future.
Superconductivity is a phenomenon exhibited by some materials which offer zero resistance to flow of electric current through them under conditions of low temperature. The source of resistance is collision of conduction electrons with nuclei or impurities. Since these collisions are almost absent the resistance is practically zero. The problem with practical use of superconductors is that they retain superconducting nature only at very low temperatures which is unsuitable for normal use. If superconductivity could exist at higher temperatures, lots of power must have been saved which gets wasted in transporting electric current through wires from power grid to homes or industries. Superconductors could also be used to make faster computers with a lot less heat production.
How can the Universe expand, if it is already infinite? Give a simple example that might help the president understand this, if he or she were to ask you.
The Universe has been expanding since the Big Bang. The space in the Universe is infinite & so the Universe is expanding into infinity. The best example to describe the expansion of the Universe is baking of a load of raisin bread. As the bread bakes, the dough grows to a larger size & the raisins on the loaf move further apart from each other. Infinite space expands into infinite space. There is no center for the Universe since it is infinite. The galaxies just keep moving further apart since there is plenty of space available.
What usual concepts of time are upset by the theory of relativity? What do most people accept as obvious that turns out not to be true?
The concept of time for a moving object is that it will always follow the time of the rest object. But the concept of time dilation in special theory if relativity make upset of its usual concept. Most people think that the mass of an object is an intrinsic property & it is impossible to change & people accept it as obvious. But, the special theory of relativity shows that it will increase as speed of the object is increased & proves that the usual concept is wrong.
How can invisible light be used to purify water?
The micro organisms in water are killed with a 12 second exposure to the UV rays. The germicidal lamp is made out of special quartz class that permits UV rays to pass through which emits radiation which results in maximum organisms being destroyed.
Quantum physics has properties that seem very strange to someone who doesn't recognize that particles have wavelike behavior. What behavior of electrons would be impossible to understand based on classical (nonquantum) physics? What behavior of light would be impossible to understand based on the classical theory of light (i.e., light as a wave, not a quantum wave)?
The particle nature of electrons is predicted in the classical theory. Superconductivity cannot be explained without using wave nature of electrons. According to classical theory, light behaves as a wave. Photoelectric effect cannot be explained using wave theory of light because light behaves as a particle & is quantized.
Lasers have several properties that make them special. Describe what these properties are. For each special property, describe practical applications that take advantage of it.
The photons emitted in the laser light have virtually identical frequency. The photons emitted are in the same direction. Laser light has a single frequency which makes it useful in communication. -supermarket bar code reader uses a laser with a detector to read bar codes on different items. The laser in the bar code reader is moved rapidly so as to scan the whole of the bar code. The detector can differentiate between the light from external surrounding because the laser light consists of a single frequency. - CDs are a compact disk that has music recorded on a thin layer of aluminum buried inside of the plastic. The focusing property of lasers is made into use.
Light is a wave. But according to quantum mechanics, it is also quantized. What does that mean? Describe some practical applications of light that make use of the fact that both it and energy levels are sometimes quantized.
The quantization of light means that light travels in form of small packets called quantum. Light itself is not continuous but behaves like particles. Spectral fingerprint is one example that manifests quantization of energy as well as quantization of light. When electron transits from a higher energy level to a lower energy level a photon is emitted. Emitted light is quantized & only certain frequencies or colors are allowed. Photoelectric effect is another example in which quantization of light & quantization of energy levels are used. Election emission is spontaneous which implies that light behaves as particles & is a direct manifestation of quantization light.
What is the strongest evidence for global warming? What part of this is attributed to human activity?
The strongest evidence for global warming is increase in average temperature of the Earth. There is a 90% chance for the rise in the temperature of some in the last 50 years is due to human beings. In the next 50 years it may increase dangerously.
Physicists often say that people will never be able to travel at the speed of light. Explain why they believe that.
To reach the speed of light, the required energy that has to be supplied to this object is infinity & never possible. The physicist says that the people will never be able to travel at the speed of the light.
Discuss the warming of Alaska. What is known about it? Is it real? Does it match expectations? How can people be misled by the observed fluctuations, either to affirm their prior belief that Alaska illustrates warming, or to deny it?
Transportation, forests, ecosystems & the economy of Alaska is badly effected due to the melting of permafrost. Permafrost is the frozen ground located one to two feet below the surface in cold regions, in which a large part of Alaska is built on. The temperature record of Alaska shows that the warming of Alaska is real & documented. Depending on how the temperature records of Alaska are interpreted, the general public may be misled by the observed fluctuations, either to affirm their prior belief that Alaska is warming, or to deny it.
A black light is designed to emit
UV
The best kind of radiation to purify water
UV
Sunburn is usually caused by
UV radiation
Multispectral refers to
UV, IR, and visible
For the Earth to become a black hole, it would have to be reduced to the size of
a coin
a transistor is
a device that can amplify or turn AC to DC
A light year is
a distance
If the sun were made into a black hole, its radius would be approximately
a few kilometers
A galaxy is
a large collection of stars
The quantum chain reaction refers to
a laser
What is Nemesis
a theoretical star that orbits the Sun, making comets and asteroids veer toward the Earth
Invisible light includes ultraviolet light, also called UV. What is this? How does it affect our everyday lives? What are its practical uses and applications?
a type of energy that comes to Earth from the Sun, can damage skin and cause cancer, and is mostly absorbed by the ozone layer
the energy gap is important for (choose all that are correct)
all of the above
which of the following are electromagnetic waves?
all the above
A positron is
an anti-electron
an electron is in orbit around a proton. what is the maximum number of orbits it can be in at the same time?
any number
If we turn the Sun into a black hole, then the force on the Earth will
be unchanged
which of the following is not a zero-mass particle?
beta ray
Dew forms when the ground cools
by emitting IR
A few years ago, a certain kind of spray can was banned. These were the cans that used
chlorofluorocarbons (CFC's)
Which fossil fuel produces the most CO2, per pound, when burned?
coal
The energy of a photon depends on
color
Which of the following exposes a person to the kind of radiation that can cause cancer
computer-aided tomography (CAT) scans
The expansion of the Universe is accelerating. Physicists attribute this to
dark energy
Most of the mass of the Universe is
dark matter
most of the mass in the universe is made of
dark matter
at very high speed, all of these change except
electric charge
If you sleep under a tree you wont get wet from morning dew. That's because the tree
emits infrared radiation
The advertising slogan "whiter than white" means that the material
emits visible light
Transistors use semiconductors with different
energy gaps
To make clothes appear extra clean, manufactures apply
fluorescent dyes
Which of the following has the highest frequency?
gamma rays
If you double the absolute temperature of an object, the wavelength of the emitted light
gets shorter by a factor of 2
Sunlight is brightest in which color?
green
To become a black hole, an object must
have been formed in a supernova explosion
tachyons
have never been observed
when a person moves at a velocity near the speed of light, which of the following are true--compared to a person at rest? (Choose all that apply)
he doesn't age as rapidly, his mass increases, his energy increases
Infrared radiation can (choose all that apply)
help snakes locate prey
To make a black hole, we need
high mass in a small radius
MRI maps the distribution of which element to produce and image
hydrogen
What was made in the first 4 minutes after the Big Bang (all that apply)
hydrogen & helium
Thanks to humans, the carbon dioxide in the atmosphere has
increased by about 36%
when a radioactive rock travels near the speed of light, its mass
increases and there are fewer decays
If you double the absolute temperature the total radiation
increases by 16
when a particle approaches the speed of light, its mass approaches
infinity
when the velocity of an object with rest mass m0 approaches the speed of light, its energy approaches:
infinity
A heat seeking missle actually aims itself toward
infrared light
Which kind of light has the longest wavelength?
infrared light
Because of their warmth humans emit primarily
infrared radiation
In total darkness, you can see people if you have a camera that is sensitive to
infrared radiation
the lorentz contraction says that a football thrown past your face
is shorter by a factor of gamma
the speed of a massless particle
is the same to all observers
Doppler shift for galaxies
is usually toward red
as the velocity of a moving object approaches the speed of light, what happens to its energy?
it goes to infinity
electrons cannot go as fast as light because
it would take infinite energy
a particle travels at the speed of light. We conclude that
its rest mass is zero
we measure that a particle travels at the speed of light. we conclude that
its rest mass is zero
Compact disk readers use
lasers
Stimulated emission is important for
lasers
Which of the following quantities do not depend on velocity?
m0
Each of these make use of infrared radiation except
measurements of wave velocities in the ocean
Ice in Antarctica is
melting, contradicting global warming predictions
Cell Phones emit
microwaves
the Lorentz contraction refers to the fact that
moving objects get shorter
"cool roofs"
must reflect infrared
Jane and Tom synchronize their watches on Earth. Jane remains on the Earth while tom takes a round-trip to Pluto at near light speed. when they get back together, whose clock is correct?
neither clock is correct (since earth is always moving too)
identify which are the particles that pass easily through the earth
neutrinos
the observation of neutrino decay proves that
neutrinos do have mass
Quantum computers are
not yet very good at anything
an astronaut Alice makkes a round-trip at 3/5 the speed of light. Her twin Bob stays on the Earth. When Alice returns, Bob is
older than Alice
a laser operates on the principle of
photon avalanche
the photoelectric effect is important for all of the following except
polarized sunglasses
The original name for the microwave oven was
radar range
According to the text, wind power is
rapidly growing, with wind turbines delivering twice the power they did four years ago
Most of the energy of an ordinary tungsten-filament lightbulb is emitted
red
As an object gets hotter and hotter, the color of its glow will change from
red, to yellow, to white, to blue
Clean coal
refers to coal used at a power plant with carbon capture and storage (CCS)
Microwave ovens use radiation with a wavelength
same as radar
Radio waves and xrays have the
same speed
When you look at a galaxy 5 billion light years away, you
see this galaxy as it was 5 billion years ago
Which of the following depend on an energy gap? (Choose all that apply)
semiconductors, superconductors, lasers
A key feature of the Kyoto treaty is that it
set up a method to trade carbon credits
light from the Andromeda Galaxy reaches us in
several millions of years
a moving object is
shorter and younger
computer circuits are based on which material?
silicon
neutrinos are believed to have mass
small, but not zero
What is the cause for "windburn"
solar UV
Dark energy makes the Universe
speed up
Quanta are not observed from water waves because
such waves are not quantized
Choose all of the following that are NOT part of our solar system
the andromeda Galaxy
The discovery of dark energy means that
the expansion of the universe is accelerating
Which of the following statements about the ozone layer is not true?
the location of the ozone layer is the tropopause
The clouds in the thunderstorms rise until they reach
the ozone layer
xerox machines make use of
the photoelectric effect
lasers are useful because (choose all that are correct)
their light is single frequency, they can be well collimated, they can be made intense
To tell hydrogen from helium, look at
their visible spectrum
superconducting materials allow electrons to move without loss of energy because
there is an energy gap
In the Big Bang theory
there is no center to the universe
in everyday life, we don't see the effects of relativity because
they are too small to detect easily
tachyons are particles that
travel faster than c
if Muller discovers a new, energetic particle (the "Mulleron") that has zero mass, then we can conclude that the Mulleron
travels at the speed of light
The phosphor of a fluorescent lightbulb turns which of these into visible light
ultraviolet light
Cancer is most likely to be caused by
ultraviolet radiation
The ozone layer is created by and absorbs
ultraviolet radiation
The microwaves in a microwave oven mostly heat
water
dark matter is made of
we dont know
Oxygen and nitrogen were created
within a star
Which of the following is best for seeing the calcium in bones
x-ray
Invisible light includes
x-rays, UV, and IR
according to relativity theory, the energy of an object of mass m0 that is moving at velocity v is
ym0c^2
in the twin effect, the traveling twin is
younger
Cooling during the Little Ice Age (AD 1350 to 1850) was approximately
2 degrees F
In the United States, nuclear power produces what percentage of the electricity?
20%
The greenhouse effect currently warms the Earth by approximately
35 degrees F
Carbon dioxide in the atmosphere has increased over the past 100 years by about
36%
Which of the following is an advanced method that uses x-rays
CAT
The country that produces the most carbon dioxide each year is
China
Discuss what is meant by cool colors, especially with regard to paint. What problem does a cool color address? How does it work?
Cool colors must reflect infrared radiation, even though it absorbs visible light it reflects infrared waves. The roofs are painted with a paint that reflects the infrared radiation & absorbs visible light, therefore the roof doesn't appear shiny, it is cool as it reflects the IR.