Question

26. What do you mean by half-life and average life of a radioactive substance? Establish disintegration formula(N = No 6") for radioactive substance. ​

Answer 1

Explanation:

Half life of a radioactive substance(τ

1/2

) measures the time it takes for a given amount of the substance to become reduced by half as a consequence of decay, and therefore, the emission of radiation.

It is related to radioactive decay constant k as τ

1/2

=

k

ln2

.

Also its relation with mean life λ

m

=

k

1

is

τ

1/2

=λ

m

ln2

Answer 2

♦ Half life of a radioactive substance :

→ The time in which half of the original number of parent atoms in the samples undergoes disintegration.

→ The formula for the half life is given by

• T = 0.693 / decay constant

→ Half life of a radioactive substance is inversely proportional to the decay constant.

♦ Average life of a radioactive substance :

→ The average life of a radioactive substance is given by the ratio of the total lifetime of all the individual parent atoms to the total number of such atoms present in the samples.