Units of Measurement

Basic Units

Becquerel (Bq): The unit of radioactive decay. One Bq is equal to one decay per second.

Derived Units

Gray (Gy): The unit for absorbed dose of radiation. One Gy is equal to one joule per kilogram.
Sievert (Sv): The unit for equivalent dose of radiation. It measures the biological effect of radiation.

Descriptions and Comparisons

The Becquerel (Bq) is the modern unit for measuring radioactivity. It is relatively small unit, and for practical purposes, quantities of radioactivity are often stated in kBq (1,000 Bq), MBq (one million Bq), GBq, and so on.
Curie (Ci): This is another unit of radioactivity frequently used in nuclear physics, named after the famous scientist Marie Curie. One Curie equals 3.7x10^10 decays per second, or 37 GBq. This explains why the Becquerel is seen as a tiny measurement - there are 37 billion Bq in a single Curie!
The gray (Gy) and the sievert (Sv) are used to quantify the impact of ionising radiation on human tissue.
One gray is equivalent to absorbing one joule of radiation energy per kilogram of matter. However, not all types of radiation have the same biological effect - this is where the sievert comes in.
The sievert takes into account the type of radiation and its biologically damaging effects. Hence, doses of ionising radiation are often specified in terms of sieverts, to reflect the harm done to human tissue.

Converting Units

It’s vital to understand how to convert between these units. For example, 1 Gy = 1 Sv for gamma and beta radiation, but for alpha particles, 1 Gy = 20 Sv due to their high ionising power.
For radioactivity, remember that 1 Ci = 3.7x10^10 Bq. This may prove useful in calculations or conversion tasks.

By understanding these units and their applications, you’re able to accurately describe and quantify the levels and effects of radioactivity in different circumstances.