Wednesday, January 12, 2011
Tuesday, January 11, 2011
1.WRITE THE USES OF RADIOACTIVE DECAY.
2.WHAT IS THE SI UNIT AND OLD UNIT OF RADIOACTIVITY.
3.BETA PARTICLES COME FROM THE NUCLEUS AND THEY ARE ELECTRONS, BUT THERE NO ELECTRONS INSIDE THE NUCLEUS. EXPLAIN THIS PARADOX.
2.WHAT IS THE SI UNIT AND OLD UNIT OF RADIOACTIVITY.
3.BETA PARTICLES COME FROM THE NUCLEUS AND THEY ARE ELECTRONS, BUT THERE NO ELECTRONS INSIDE THE NUCLEUS. EXPLAIN THIS PARADOX.
APPLICATION OF RADIOACTIVE DECAY
Applications of radioactivity
In medicineRadioisotopes have found extensive use in diagnosis and therapy, and this has given rise to a rapidly growing field called nuclear medicine. These radioactive isotopes have proven particularly effective as tracers in certain diagnostic procedures. As radioisotopes are identical chemically with stable isotopes of the same element, they can take the place of the latter in physiological processes. Moreover, because of their radioactivity, they can be readily traced even in minute quantities with such detection devices as gamma-ray spectrometers and proportional counters. Though many radioisotopes are used as tracers, iodine-131, phosphorus-32, and technetium-99m are among the most important. Physicians employ iodine-131 to determine cardiac output, plasma volume, and fat metabolism and particularly to measure the activity of the thyroid gland where this isotope accumulates. Phosphorus-32 is useful in the identification of malignant tumours because cancerous cells tend to accumulate phosphates more than normal cells do. Technetium-99m, used with radiographic scanning devices, is valuable for studying the anatomic structure of organs.
Such radioisotopes as cobalt-60 and cesium-137 are widely used to treat cancer. They can be administered selectively to malignant tumours and so minimize damage to adjacent healthy tissue.
In industryForemost among industrial applications is power generation based on the release of the fission energy of uranium (see nuclear fission; nuclear reactor: Nuclear fission reactors). Other applications include the use of radioisotopes to measure (and control) the thickness or density of metal and plastic sheets, to stimulate the cross-linking of polymers, to induce mutations in plants in order to develop hardier species, and to preserve certain kinds of foods by killing microorganisms that cause spoilage. In tracer applications radioactive isotopes are employed, for example, to measure the effectiveness of motor oils on the wearability of alloys for piston rings and cylinder walls in automobile engines. For additional information about industrial uses, see radiation: Applications in science and industry.
In scienceResearch in the Earth sciences has benefited greatly from the use of radiometric-dating techniques, which are based on the principle that a particular radioisotope (radioactive parent) in geologic material decays at a constant known rate to daughter isotopes. Using such techniques, investigators have been able to determine the ages of various rocks and rock formations and thereby quantify the geologic time scale (see geochronology: Absolute dating). A special application of this type of radioactivity age method, carbon-14 dating, has proved especially useful to physical anthropologists and archaeologists. It has helped them to better determine the chronological sequence of past events by enabling them to date more accurately fossils and artifacts from 500 to 50,000 years old.
Radioisotopic tracers are employed in environmental studies, as, for instance, those of water pollution in rivers and lakes and of air pollution by smokestack effluents. They also have been used to measure deep-water currents in oceans and snow-water content in watersheds. Researchers in the biological sciences, too, have made use of radioactive tracers to study complex processes. For example, thousands of plant metabolic studies have been conducted on amino acids and compounds of sulfur, phosphorus, and nitrogen.
In medicineRadioisotopes have found extensive use in diagnosis and therapy, and this has given rise to a rapidly growing field called nuclear medicine. These radioactive isotopes have proven particularly effective as tracers in certain diagnostic procedures. As radioisotopes are identical chemically with stable isotopes of the same element, they can take the place of the latter in physiological processes. Moreover, because of their radioactivity, they can be readily traced even in minute quantities with such detection devices as gamma-ray spectrometers and proportional counters. Though many radioisotopes are used as tracers, iodine-131, phosphorus-32, and technetium-99m are among the most important. Physicians employ iodine-131 to determine cardiac output, plasma volume, and fat metabolism and particularly to measure the activity of the thyroid gland where this isotope accumulates. Phosphorus-32 is useful in the identification of malignant tumours because cancerous cells tend to accumulate phosphates more than normal cells do. Technetium-99m, used with radiographic scanning devices, is valuable for studying the anatomic structure of organs.
Such radioisotopes as cobalt-60 and cesium-137 are widely used to treat cancer. They can be administered selectively to malignant tumours and so minimize damage to adjacent healthy tissue.
In industryForemost among industrial applications is power generation based on the release of the fission energy of uranium (see nuclear fission; nuclear reactor: Nuclear fission reactors). Other applications include the use of radioisotopes to measure (and control) the thickness or density of metal and plastic sheets, to stimulate the cross-linking of polymers, to induce mutations in plants in order to develop hardier species, and to preserve certain kinds of foods by killing microorganisms that cause spoilage. In tracer applications radioactive isotopes are employed, for example, to measure the effectiveness of motor oils on the wearability of alloys for piston rings and cylinder walls in automobile engines. For additional information about industrial uses, see radiation: Applications in science and industry.
In scienceResearch in the Earth sciences has benefited greatly from the use of radiometric-dating techniques, which are based on the principle that a particular radioisotope (radioactive parent) in geologic material decays at a constant known rate to daughter isotopes. Using such techniques, investigators have been able to determine the ages of various rocks and rock formations and thereby quantify the geologic time scale (see geochronology: Absolute dating). A special application of this type of radioactivity age method, carbon-14 dating, has proved especially useful to physical anthropologists and archaeologists. It has helped them to better determine the chronological sequence of past events by enabling them to date more accurately fossils and artifacts from 500 to 50,000 years old.
Radioisotopic tracers are employed in environmental studies, as, for instance, those of water pollution in rivers and lakes and of air pollution by smokestack effluents. They also have been used to measure deep-water currents in oceans and snow-water content in watersheds. Researchers in the biological sciences, too, have made use of radioactive tracers to study complex processes. For example, thousands of plant metabolic studies have been conducted on amino acids and compounds of sulfur, phosphorus, and nitrogen.
RADIOACTIVITY
Decay types
Radio nuclides of different types can be involved in several different reactions that produce radiant energy. The three main types of ionizing radiation are alpha, beta, and gamma.
Alpha decay- Two protons and two neutrons emitted from nucleus
Beta decay- A neutron emits an electron and an antineutrino and becomes a proton
Gamma decay- Excited nucleus releases a high-energy photon
Property Alpha radiation Beta radiation Gamma radiation
Composition Alpha particle Beta particle Electromagnetic radiation
Symbol α β γ
Charge 2+ 1- 0
Mass 4 1/1837 0
Penetrating power Low Moderate Very high
Monday, January 10, 2011
FOLLOW UP OF THE CHAPTER
1. GIVE THE METHOD OF FINDING THE AGE OF FOSSIL.
2.HOW MANY PROTONS AND NEUTRONS ARE LOST FROM THE NUCLEUS DURING AN ALPHA EMISSION.
3. HOW MANY ELECTRONS ARE EMMIT DURING A BETA EMISSION
4. WHAT IS PRINCIPLE OF FISSION BOMB
5. WHAT ARE THE DIFFERENT TYPES OF NUCLEAR REACTOR
6. WHY DO LIGHTER ELEMENTS PREFER TO FUSE
7. WHAT ARE THE DIFFICULTIES FOR THE CONTROLLED FUSION REACTION
8. WHICH ARE THE CONSTITUENTS OF NUCLEUS
9. WHAT HAPPENS TO THE SIZE OF NUCLEUS WHEN THE NUMBER OF NUCLEONS IS INCREASED.
10. DEFINE HALF LIFE PERIOD,MEAN LIFE
11. WHAT IS RADIOACTIVITY.
12.WHAT ARE THE TWO UNITS OF RADIOACTIVITY.
13.DEFINE THE TWO UNITS
2.HOW MANY PROTONS AND NEUTRONS ARE LOST FROM THE NUCLEUS DURING AN ALPHA EMISSION.
3. HOW MANY ELECTRONS ARE EMMIT DURING A BETA EMISSION
4. WHAT IS PRINCIPLE OF FISSION BOMB
5. WHAT ARE THE DIFFERENT TYPES OF NUCLEAR REACTOR
6. WHY DO LIGHTER ELEMENTS PREFER TO FUSE
7. WHAT ARE THE DIFFICULTIES FOR THE CONTROLLED FUSION REACTION
8. WHICH ARE THE CONSTITUENTS OF NUCLEUS
9. WHAT HAPPENS TO THE SIZE OF NUCLEUS WHEN THE NUMBER OF NUCLEONS IS INCREASED.
10. DEFINE HALF LIFE PERIOD,MEAN LIFE
11. WHAT IS RADIOACTIVITY.
12.WHAT ARE THE TWO UNITS OF RADIOACTIVITY.
13.DEFINE THE TWO UNITS
QUESTIONS
1.PREDICT THE CONSEQUENCE OF NUCLEAR FISSION.
2.WHY ARE THE CONTROL RODS MADE OF CADMIUM.
3. WHY HEAVY WATER IS USED AS A MODERATOR.
4.NUCLEAR FUSION IS CALLED THERMONUCLEAR REACTION WHY?
5.HOW IS ENERGY PRODUCED IN STARS.
6.WHAT IS THE ORDER OF TEMPERATURE FOR FUSION REACTION565565656
2.WHY ARE THE CONTROL RODS MADE OF CADMIUM.
3. WHY HEAVY WATER IS USED AS A MODERATOR.
4.NUCLEAR FUSION IS CALLED THERMONUCLEAR REACTION WHY?
5.HOW IS ENERGY PRODUCED IN STARS.
6.WHAT IS THE ORDER OF TEMPERATURE FOR FUSION REACTION565565656
DIFFERENCE BETWEEN FISSION AND FUSSION
Nuclear Fission vs Nuclear Fusion66666
Natural occurrence of the process:Fission reaction does not normally occur in nature.Fusion occurs in stars, such as the sun.
Byproducts of the reaction:Fission produces many highly radioactive particles.Few radioactive particles are produced by fusion reaction, but if a fission "trigger" is used, radioactive particles will result from that.
Energy Ratios:The energy released by fission is a million times greater than that released in chemical reactions; but lower than the energy released by nuclear fusion.The energy released by fusion is three to four times greater than the energy released by fission.
Nuclear weapon:One class of nuclear weapon is a fission bomb, also known as an atomic bomb or atom bomb.One class of nuclear weapon is the hydrogen bomb, which uses a fission reaction to "trigger" a fusion reaction
Definition:Fission is the splitting of a large atom into two or more smaller ones.Fusion is the fusing of two or more lighter atoms into a larger one.
Conditions:Critical mass of the substance and high-speed neutrons are required.High density, high temperature environment is required.
Energy requirement:Takes little energy to split two atoms in a fission reaction.Extremely high energy is required to bring two or more protons close enough that nuclear forces overcome their electrostatic repulsion.
Natural occurrence of the process:Fission reaction does not normally occur in nature.Fusion occurs in stars, such as the sun.
Byproducts of the reaction:Fission produces many highly radioactive particles.Few radioactive particles are produced by fusion reaction, but if a fission "trigger" is used, radioactive particles will result from that.
Energy Ratios:The energy released by fission is a million times greater than that released in chemical reactions; but lower than the energy released by nuclear fusion.The energy released by fusion is three to four times greater than the energy released by fission.
Nuclear weapon:One class of nuclear weapon is a fission bomb, also known as an atomic bomb or atom bomb.One class of nuclear weapon is the hydrogen bomb, which uses a fission reaction to "trigger" a fusion reaction
Definition:Fission is the splitting of a large atom into two or more smaller ones.Fusion is the fusing of two or more lighter atoms into a larger one.
Conditions:Critical mass of the substance and high-speed neutrons are required.High density, high temperature environment is required.
Energy requirement:Takes little energy to split two atoms in a fission reaction.Extremely high energy is required to bring two or more protons close enough that nuclear forces overcome their electrostatic repulsion.
NUCLEAR FUSSION
NUCLEAR FUSION
The process in which two or more light nuclei are combined into a single nucleus with the release of tremendous amount of energy is called as nuclear fusion. Like a fission reaction, the sum of masses before the fusion (i.e. of light nuclei) is more than the sum of masses after the fusion (i.e. of bigger nucleus) and this difference appears as the fusion energy. The most typical fusion reaction is the fusion of two deuterium nuclei into helium.
1H1 + 1H2 —> 2He4 + 21.6 MeV
For the fusion reaction to occur, the light nuclei are brought closer to each other (with a distance of 10–14 m). This is possible only at very high temperature to counter the repulsive force between nuclei. Due to this reason, the fusion reaction is very difficult to perform. The inner core of sun is at very high temperature, and is suitable for fusion, in fact the source of sun's and other star's energy is the nuclear fusion reaction
PLS ADD VEDIO CLIP OF NUCLEAR FUSION
The production of an abundant and clean energy is one of the grail of physics and modern technology. Among the candidates identified, nuclear fusion is among the favorites. After several decades of efforts, scientists are able to overcome one by one the obstacles they face in achieving control this form of energy. Two developments in this area have been announced in recent days.
The reactions of nuclear fusion
The nuclear fusion reactions are those that take place inside stars. In this process, nuclei of light atoms fuse to form heavier atoms. The reaction product, the same mass of fuel, 4 to 5 times more energy than fission reactions that are used in existing nuclear power plants. However, this nuclear energy is much more difficult to master.
Fusion reactions occur at temperatures of several tens of millions of degrees. In these circumstances, the matter is in the form of a plasma. The first challenge is therefore confined to this set of highly energetic charged particles. The second is to obtain a density very high regard for pushing the nuclei of atoms, which naturally repel the effect of electrical forces to meet and merge. In the case of a star, obtaining high temperatures and high densities is carried out simultaneously by the gravitational collapse of the star under its own weight. Fusion reactions occur when the energy required to offset the collapse and ensure stability of the star. At least until the total use of fuels which causes the death of the star.
Fission and fusion
To reproduce the nuclear fusion on Earth, we must succeed in maintaining a state controlled to a certain quantity of matter at temperatures and densities very high to cause fusion reactions and especially sustain the process to provide energy continuously. This condition is essential and is a difference between the reactions of fusion and fission.
The fission reactions occur in string. An neutron posted a solid nucleus destabilizes its energy causing fission into two nuclei of mass less and producing neutrons which in turn will cause the fission of nuclei. The reaction self-sustaining, continues as the fuel is available. This presents a major advantage to ensure the continued production of energy or when trying to make a very powerful bomb. Advantage can quickly become a disadvantage if the reaction gets carried away and causes the complete fusion reactor and radioactive pollution that ensues as happened at Chernobyl in 1986. The risk of runaway reactions is not the case in the process of nuclear fusion as soon as the temperature and / or density of matter are not met, the reaction stops.
The issue of energy production by fission is therefore to prevent the risk of runaway reaction while the production of fusion energy is to keep the system under conditions permitting the realization of reactions. The fission process is simple to implement, but risky when the merger is a complex process but does not present similar risks. Fusion has also other advantages over fission. The proposed reagents, deuterium and tritium (heavy isotope of hydrogen) are relatively abundant. Chemically equivalent to hydrogen, deuterium replaces in molecules of up to 0.015%. This may seem low but the abundance of hydrogen-water molecule contains two atoms to one oxygen atom, provides abundance of deuterium (it should however be extracted molecules). If tritium is different. This is a radioactive element with a period of very short life of just over 12 years. Thus there is only very small quantities naturally but its synthesis is under control for several decades. Combustible materials for nuclear fusion are far more abundant than those available for fission, that is to say uranium.
The other major advantage of fusion over fission of waste products. The reactions of nuclear fission produces radioactive waste whose lifetimes are very long, the order of several hundreds of thousands of years. The problem with these waste is not so much of their dangerousness as the difficulty to store securely over periods as long. What are the geological terrain that will remain stable for the next 200,000 years? How to ensure transmission of the memory of those storages? Simply put: what should we write about the waste to be sure of being understood in 100,000 years? In the case of fusion, radioactive waste, in much smaller amounts, have lifetimes shorter of the order of hundred years.
Control of energy production by nuclear fusion presents so many advantages: the existence of relatively abundant fuel, a very high ratio between the amount of fuel required and the energy produced a quantity of hazardous waste relatively low. However, the key processes occurring inside stars and to start the fusion reaction-the-gravitational collapse can not be reproduced on Earth. To create the conditions for nuclear fusion, two processes have been investigated: magnetic confinement and inertial confinement.
The process in which two or more light nuclei are combined into a single nucleus with the release of tremendous amount of energy is called as nuclear fusion. Like a fission reaction, the sum of masses before the fusion (i.e. of light nuclei) is more than the sum of masses after the fusion (i.e. of bigger nucleus) and this difference appears as the fusion energy. The most typical fusion reaction is the fusion of two deuterium nuclei into helium.
1H1 + 1H2 —> 2He4 + 21.6 MeV
For the fusion reaction to occur, the light nuclei are brought closer to each other (with a distance of 10–14 m). This is possible only at very high temperature to counter the repulsive force between nuclei. Due to this reason, the fusion reaction is very difficult to perform. The inner core of sun is at very high temperature, and is suitable for fusion, in fact the source of sun's and other star's energy is the nuclear fusion reaction
PLS ADD VEDIO CLIP OF NUCLEAR FUSION
The production of an abundant and clean energy is one of the grail of physics and modern technology. Among the candidates identified, nuclear fusion is among the favorites. After several decades of efforts, scientists are able to overcome one by one the obstacles they face in achieving control this form of energy. Two developments in this area have been announced in recent days.
The reactions of nuclear fusion
The nuclear fusion reactions are those that take place inside stars. In this process, nuclei of light atoms fuse to form heavier atoms. The reaction product, the same mass of fuel, 4 to 5 times more energy than fission reactions that are used in existing nuclear power plants. However, this nuclear energy is much more difficult to master.
Fusion reactions occur at temperatures of several tens of millions of degrees. In these circumstances, the matter is in the form of a plasma. The first challenge is therefore confined to this set of highly energetic charged particles. The second is to obtain a density very high regard for pushing the nuclei of atoms, which naturally repel the effect of electrical forces to meet and merge. In the case of a star, obtaining high temperatures and high densities is carried out simultaneously by the gravitational collapse of the star under its own weight. Fusion reactions occur when the energy required to offset the collapse and ensure stability of the star. At least until the total use of fuels which causes the death of the star.
Fission and fusion
To reproduce the nuclear fusion on Earth, we must succeed in maintaining a state controlled to a certain quantity of matter at temperatures and densities very high to cause fusion reactions and especially sustain the process to provide energy continuously. This condition is essential and is a difference between the reactions of fusion and fission.
The fission reactions occur in string. An neutron posted a solid nucleus destabilizes its energy causing fission into two nuclei of mass less and producing neutrons which in turn will cause the fission of nuclei. The reaction self-sustaining, continues as the fuel is available. This presents a major advantage to ensure the continued production of energy or when trying to make a very powerful bomb. Advantage can quickly become a disadvantage if the reaction gets carried away and causes the complete fusion reactor and radioactive pollution that ensues as happened at Chernobyl in 1986. The risk of runaway reactions is not the case in the process of nuclear fusion as soon as the temperature and / or density of matter are not met, the reaction stops.
The issue of energy production by fission is therefore to prevent the risk of runaway reaction while the production of fusion energy is to keep the system under conditions permitting the realization of reactions. The fission process is simple to implement, but risky when the merger is a complex process but does not present similar risks. Fusion has also other advantages over fission. The proposed reagents, deuterium and tritium (heavy isotope of hydrogen) are relatively abundant. Chemically equivalent to hydrogen, deuterium replaces in molecules of up to 0.015%. This may seem low but the abundance of hydrogen-water molecule contains two atoms to one oxygen atom, provides abundance of deuterium (it should however be extracted molecules). If tritium is different. This is a radioactive element with a period of very short life of just over 12 years. Thus there is only very small quantities naturally but its synthesis is under control for several decades. Combustible materials for nuclear fusion are far more abundant than those available for fission, that is to say uranium.
The other major advantage of fusion over fission of waste products. The reactions of nuclear fission produces radioactive waste whose lifetimes are very long, the order of several hundreds of thousands of years. The problem with these waste is not so much of their dangerousness as the difficulty to store securely over periods as long. What are the geological terrain that will remain stable for the next 200,000 years? How to ensure transmission of the memory of those storages? Simply put: what should we write about the waste to be sure of being understood in 100,000 years? In the case of fusion, radioactive waste, in much smaller amounts, have lifetimes shorter of the order of hundred years.
Control of energy production by nuclear fusion presents so many advantages: the existence of relatively abundant fuel, a very high ratio between the amount of fuel required and the energy produced a quantity of hazardous waste relatively low. However, the key processes occurring inside stars and to start the fusion reaction-the-gravitational collapse can not be reproduced on Earth. To create the conditions for nuclear fusion, two processes have been investigated: magnetic confinement and inertial confinement.
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