Question

State the law of radioactive disintegration.

Answer 1

Hint: You can start the solution by describing what radioactivity is, write down some of its uses and its shortcomings. Then move on to describe the radioactive disintegration law and also write down its equation i.e. $\dfrac{{\Delta N}}{{\Delta t}} \propto N$.

Complete step-by-step answer:
Before talking about radioactive disintegration law, let’s first discuss why it is used.
The radioactive disintegration law is used to measure the rate of radioactive decay.
Radioactive decay or nuclear decay is a process that occurs in an unstable element, by which it loses energy in the form of radiation. Any material that has an unstable nuclei is termed as a radioactive material. There are 3 types of major radioactive decays i.e. alpha decay (releases alpha particle), beta decay (releases beta particles) and gamma decay (releases gamma particles).
Radioactivity is used in nuclear power to generate energy and also in nuclear weapons. But radioactive material used in power plants, after its use becomes radioactive waste and it is very difficult to safely dispose of it.
Radioactive disintegration law – This law states that the number of radioactive nuclei that decay per unit time ($1\sec$) is directly proportional to the total number of radioactive nuclei in any given sample.
By radioactive disintegration law, we know
$\dfrac{{\Delta N}}{{\Delta t}} \propto N$
$\Rightarrow \dfrac{{\Delta N}}{{\Delta t}} = \lambda N$
Here,
$\Delta N =$Change in the number of radioactive nuclei in the sample or the number of radioactive nuclei that decayed.
$\Delta t =$Time
$N =$Total number of the total radioactive nuclei in any given sample
$\lambda =$ Radioactive decay constant or also known as the disintegration constant

Note – We discussed above the concept of radioactivity, as to why it occurs, it is quite simple. Remember every atom, molecule or body in this whole universe has the tendency to remain in the lowest energy state possible because low energy state means more stability. Radioactive nuclei naturally have excess energy and thus release energy in the form of radiation to become more stable.