Question

What is the S.I. unit of activity?

Answer 1

Radioactive decay rates are usually written in terms of their half-lives. The half-life of any given nuclear species is associated with its radiation decay. A particular radioactive material can undergo different radioactive decay paths that leads to the formation of different chemical elements. Radioactive decay of a product can be examined to find its radioactive dating.

Complete step-by-step answer:
The Becquerel is the SI derived unit of radioactivity. One Becquerel is defined as the decay of a quantity of radioactive material in which one nucleus decays per second. For applications relating to human health this is a small quantity and SI multiples of the unit are commonly used.

Additional information:
The Becquerel is named after Henri Becquerel. He shared a Nobel Prize in Physics with Pierre and Marie Curie in 1903 for their profound work in radioactivity. Due to instability of the nucleus, particles are emitted out of it and result in radioactivity. Because the nucleus experiences the strong fight between the two strongest forces in nature, it should not be astounding that there are many nuclear isotopes which are not stable and emit some kind of radiation. There are different types of radiations. The main radiations are alpha, beta and gamma radiations.

Note: Becquerel was the special name that was introduced for the reciprocal second to identify radioactivity to prevent mistakes with prefixes. For example, 1 µs$^{−1}$ would mean 106 disintegrations per second: $1\times {{({{10}^{-6}}s)}^{-1}}={{10}^{6}}{{s}^{-1}}$. The other unit that could be used for activity was Hertz (Hz) which also represents reciprocal second. Hertz is rejected because it was used for periodic phenomena but Bq was used for aperiodic phenomena like radioactivity.