Write a brief note on alpha beta and gamma rays with examples
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Alpha Particle
An alpha particle is just a helium nucleus without any electrons -- two protons and two neutrons. It has a much greater mass than beta particles, and consequently a much shorter range. Ordinarily, it travels at about a tenth of the speed of light. When a nucleus ejects an alpha particle, its atomic number decreases by 2 and its mass decreases by 4, so it is now a different element. A sheet of tissue paper or the surface layer of your skin is sufficient to stop an alpha particle, so they have relatively little penetrating power. They are more dangerous if the material emitting alpha particles has been introduced into the human body, in which case they become extremely dangerous.
Examples of this sort of nuclear transmutation are when uranium becomes thorium, or radium becomes radon gas, due to alpha decay. Alpha particles are commonly emitted by all of the larger radioactive nuclei such as uranium, thorium, actinium, and radium, as well as the transuranic elements.
Beta Particles
A beta particle is an electron. When a nucleus emits a beta particle, one of its neutrons changes into a proton, so the atomic number increases by 1 and it is now a different element. Beta particles travel at about 90 percent of the speed of light and have a hundred times more penetrating power than alpha particles; a sheet of aluminum will stop them however, and they only penetrate about a centimeter into human flesh.
The decay of technetium-99, which has too many neutrons to be stable, is anexample of beta decay. A neutron in the nucleus converts to a proton and abeta particle. The nucleus ejects thebeta particle and some gammaradiation.
Gamma Rays
Gamma rays are a high-frequency form of electromagnetic radiation, so they travel at the speed of light. Emission of gamma rays often follows emission of alpha or beta particles; when a nucleus ejects an alpha or beta particle, it is left in an excited or higher-energy state, and it can fall to a lower energy state by releasing a gamma ray photon. Gamma rays have much higher penetrating power than alpha or beta particles -- so much so, in fact,
that they can penetrate through buildings or bodies. Thick concrete or lead shields are usually needed to ensure complete protection. The high-frequency gamma rays have sufficient energy to ionize molecules in your body, which can cause damage to important macromolecules like DNA inside your cells.
An example is "gamma rays" from lightning discharges at 10 to 20 MeV, and known to be produced by the bremsstrahlung mechanism. Another example is gamma-ray bursts, now known to be produced from processes too powerful to involve simple collections of atoms undergoing radioactive decay.
hope it clarifies u dear....
An alpha particle is just a helium nucleus without any electrons -- two protons and two neutrons. It has a much greater mass than beta particles, and consequently a much shorter range. Ordinarily, it travels at about a tenth of the speed of light. When a nucleus ejects an alpha particle, its atomic number decreases by 2 and its mass decreases by 4, so it is now a different element. A sheet of tissue paper or the surface layer of your skin is sufficient to stop an alpha particle, so they have relatively little penetrating power. They are more dangerous if the material emitting alpha particles has been introduced into the human body, in which case they become extremely dangerous.
Examples of this sort of nuclear transmutation are when uranium becomes thorium, or radium becomes radon gas, due to alpha decay. Alpha particles are commonly emitted by all of the larger radioactive nuclei such as uranium, thorium, actinium, and radium, as well as the transuranic elements.
Beta Particles
A beta particle is an electron. When a nucleus emits a beta particle, one of its neutrons changes into a proton, so the atomic number increases by 1 and it is now a different element. Beta particles travel at about 90 percent of the speed of light and have a hundred times more penetrating power than alpha particles; a sheet of aluminum will stop them however, and they only penetrate about a centimeter into human flesh.
The decay of technetium-99, which has too many neutrons to be stable, is anexample of beta decay. A neutron in the nucleus converts to a proton and abeta particle. The nucleus ejects thebeta particle and some gammaradiation.
Gamma Rays
Gamma rays are a high-frequency form of electromagnetic radiation, so they travel at the speed of light. Emission of gamma rays often follows emission of alpha or beta particles; when a nucleus ejects an alpha or beta particle, it is left in an excited or higher-energy state, and it can fall to a lower energy state by releasing a gamma ray photon. Gamma rays have much higher penetrating power than alpha or beta particles -- so much so, in fact,
that they can penetrate through buildings or bodies. Thick concrete or lead shields are usually needed to ensure complete protection. The high-frequency gamma rays have sufficient energy to ionize molecules in your body, which can cause damage to important macromolecules like DNA inside your cells.
An example is "gamma rays" from lightning discharges at 10 to 20 MeV, and known to be produced by the bremsstrahlung mechanism. Another example is gamma-ray bursts, now known to be produced from processes too powerful to involve simple collections of atoms undergoing radioactive decay.
hope it clarifies u dear....
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