Mechanics MCQ Quiz Mechanics MCQ Quiz
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Nature of radioactive radiations · A number of experiments were conducted by Rutherford and others to determine the exact nature of radiations emitted during radioactive disintegration. · Rutherford and his co-workers discovered that radiations emitted by radioactive substances were of three different types; ü α-rays ü β-rays ü and (iii) γ-rays . · A radioactive atom does not emit all the three types of radiations. Ø The following experiments provide a clear analysis regarding the nature of radiations emitted by a radioactive substance. ü A small quantity of a radioactive source (radium) was placed in a hole drilled in a lead block so that radiations are allowed to proceed as a narrow beam in a particular direction towards a photographic plate. ü The lead block and the photographic plate are kept in an evacuated chamber. ü When an electr...
Natural Radioactivity -Definition and Discovery
NATURAL RADIOACTIVITY · Radioactivity is a spontaneous and self disintegrating activity exhibited by several elements having mass number greater than 206. · During the process, a complex type of radiation is emitted. · It is an irreversible process and is unaffected by physical or chemical conditions of the element. Discovery · Radioactivity was discovered accidentally by Henry Becquerel in 1896 during the study of fluorescence exhibited by double sulphate of uranium, activated by sunlight. · It was found that some sort of powerful radiations coming from the uranium salt affected the photographic plate wrapped in black paper. · Even when the photographic plate was kept in light tight box, it was affected. · Hence it ...