Question

Define one Curie.

Answer 1

Curie is basically used to measure the amount of radioactivity. This quantity is named in honour of French physicist Pierre Curie and his wife Madam Curie. Curie is described as a certain quantity of radioactive decays per second that quantity is equal to decay of 1 gram of radium per second.

Complete step by step answer:
Radioactivity basically refers to the particles which are emitted from nuclei as a result of nuclear instability. The unit for measuring the amount of radioactivity was the curie $\left( {Ci} \right)$. Initially, correspond to one gram of $radium - 226$. Recently defined as $1{\text{ }}curie{\text{ }} = {\text{ }}3.7 \times {10^{10}}$ radioactive decays per second.
And which is roughly the amount of decays that occur in 1 gram of radium per second and is ${\text{ }}3.7 \times {10^{10}}$ becquerels $\left( {Bq} \right)$.
The typical human body contains roughly $0.1{\text{ }}\mu Ci{\text{ }}\left( {14{\text{ }}mg} \right)$ of naturally occurring $potassium - 40$. A human body containing $16{\text{ }}kg$ of carbon would also have about $24$ nanograms or $0.1{\text{ }}\mu Ci$ of $carbon - 14$. Together, these would result in a total of approximately $0.2{\text{ }}\mu Ci$ or $7400$ decays per second inside the person's body (mostly from beta decay but some from gamma decay).

Note:
Power:
The power emitted in radioactive decay corresponding to one curie can be calculated by multiplying the decay energy by approximately $5.93{\text{ }}mW/MeV.$
SI units:
The SI unit of radioactivity is becquerel $\left( {Bq} \right)$ and this term has been kept after Henri Becquerel. It is defined as: The activity of a quantity of radioactive material where one decay takes place per second.
Some measuring quantities:
$1{\text{ }}curie{\text{ }} = {\text{ }}3.7 \times {10^{10}}$ radioactive decays per second
1 becquerel = 1 radioactive decay per second $= {\text{ }}2.703 \times {10^{ - 11}}{\text{ }}Ci.$
$1{\text{ }}rutherford{\text{ }} = {\text{ }}1.106$ radionuclide decays per second