12th Class Physics Sample Paper Physics Sample Paper-8

  • question_answer
    A daily wage worker, Narendra got affected by Cancer. On knowing about it all his co-workers started avoiding him, fearing that, it was contagious. Mr. Narendra felt depressed.
    Mr. Amit, a close friend immediately took him to a radiologist, who examined him and said, it was initial stage of Cancer and it can be easily cured and he also certified that it is not a communicable disease. (i) What moral values did Mr. Amit exhibit?
    (ii) What do you understand by radioactivity? How the half-life is related to the disintegration constant?
    (iii) How is average life of a radioactive sample related to its half-life?


    (i) Positive attitude, encouraging nature and creating awareness within time.
    (ii) the phenomenon of spontaneous emission of \[\alpha ,\] \[\beta \] and \[\gamma -rays\] by a substance and transforming itself into a different substance is known as radioactivity. The half-life of a substance \[({{t}_{1/2}})\] is related with its disintegration constant \[\lambda \] as
                \[{{t}_{1/2}}=\frac{0.693}{\lambda }\] (iii) The average life of a substance \[(\tau )\] is related its half-life \[({{t}_{1/2}}),\]             \[\tau =1.44{{t}_{1/2}}\]

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