Wednesday, October 31, 2018

class 10 physics half life





HALF-LIFE
AND ITS MEASUREMENT
Definition:
The time during which half of the
unstable radioactive nuclei disintegrate is called the half-life of the sample
of radioactive element
.

Explanation:
Process of radioactivity is
random
and
the rate
of
radioactive
decay
is proportional to
the number of unstable nuclei present.
In the process, a constant fraction of
large

number of unstable radioactive nuclei decays in a certain time.
 So
the life time of the unstable nuclei is
unlimited and
is difficult to measure. We can get the idea about decay rate by the term
half-life.

Example:
Radium-226 has a half-life of 1620 years,
which means that half of a radium-226 sample will be converted to other
elements by the end of 1620
years. In the next 1620 years, half of the remaining
radium
will
decay, leaving only one-fourth the original amount of radium, and so on


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