Category: Entertainment

Presentation Description

No description available.


Presentation Transcript


R adioactivity


Phenomenon in which there is a spontaneous emission of radiation from a substance is known as Radioactivity. Rays emitted by atoms due to changes in their nuclei. Therefore known as nuclear phenomenon. Definition


Light affects a photographic plate, but it cannot pass through a black paper. So, we protect the photographic plate from light by covering it by a black paper. In 1896, the scientist Henri Becquerel kept a photographic plate covered with black paper in his drawer. He had also kept a uranium sample with them. To his surprise, he found that photographic plate was clouded. History

PowerPoint Presentation:

As we know uranium is highly radioactive. Therefore he came to know that uranium gives out some kind of invisible rays that:- -> passes through black paper. -> affects a photographic plate. This way rays were named as radioactive rays. The substance emitting such rays is called radioactive substance. The above mentioned phenomenon was called as radioactivity.

PowerPoint Presentation:

Conclusion This way henri discovered the term radioactivity and its relative terms known as radioactive rays and radioactive substance.

Harmful effects:

By about 1920 people came to know that radiations from radioactive materials was harming to living organisms. The people working for companies painting dials of instruments with luminescent paints containing radium died of bone cancer. Harmful effects

PowerPoint Presentation:

Effects are as follows:- -> Loss of hair -> Cataract -> Mouth ulcer -> Damage to thyroid glands -> Breast cancer -> Burns in the skin -> Leukemia (blood cancer) -> bone cancer -> internal bleeding -> nausea -> vomiting -> headache -> some loss of white blood cells

Uses of radioactive materials:

Radioactive materials find application in many fields. -> Nuclear power :- controlled nuclear fission is used for generating electricity. It is also used for propulsion of submarines, ships, and warcrafts. Uses of radioactive materials

PowerPoint Presentation:

-> N uclear weapons :- radioactive substances like uranium are used for making atomic and hydrogen bomb. In nuclear wars when they are used they caused a destruction in which all life on earth could be wiped out. -> T racer technique :- a radioactive isotope shows its presence by emitting radiation. Thus, the movement of a substance containing the radioactive isotope in a living organism can be easily traced. The technique of tracing the movement of such a substance is called tracer technique.

Units of Measurement:

The unit used to measure radiation dosage is the rem, which stands for roentgen equivalent in man. It represents the amount of radiation needed to produce a particular amount of damage to living tissue. The total dose of rems determines how much harm a person suffers . Units of Measurement

Medical Treatment:

There is currently no effective medical treatment available for potentially fatal radiation doses. The case of the Japanese boy mentioned above illustrates an important fact about radiation sickness. The boy had probably received a dose of 450 rems or more, yet his symptoms were about the same as those of a person who received about 300 rems . Medical science has no way of telling the difference between people who have received fatal doses and will die despite all efforts and others who received less radiation and can be saved. Treatment for the ones that can be saved includes blood transfusions and bone-marrow transplants. Bone-marrow transplants rejuvenate the supply of white blood cells which was affected by the radiation. Medical Treatment

Biological Effects:

The biological effects of internally deposited radionuclides depend greatly on the activity, the bio distribution, and the removal rates of the radionuclide, which in turn depends on its chemical form, the particle size, and route of entry. Effects may also depend on the chemical toxicity of the deposited material, independent of its radioactivity. Some radionuclides may be generally distributed throughout the body and rapidly removed, as is the case with tritiated water. Biological Effects

PowerPoint Presentation:


PowerPoint Presentation:

Thank you