What is the unit of radioactivity? S.I and CGS

Radioactivity is the spontaneous disintegration of heavy element without being affected by external means. The intensity of emitted radiation is measured in different available measuring units. The measuring units may be Becquerel (Bq), Curie (Ci) or Rutherford (Rd). Standard (S.I) unit of radioactivity is Becquerel.

 

Units of Radioactivity

a) Becquerel

It is the S.I unit of radioactivity. It is represented by symbol ‘Bq’. 1 becquerel is defined as one disintegration per second.

1 Bq = 1 disintegration per second(dis/sec)

b) Curie

It is the CGS unit of radioactivity. It is represented by symbol ‘Ci’. 1 Curie is defined as 3.7 x 1010 disintegration per second. It is also equal to disintegration of 1gm of pure radium.

1 Ci = 3.7 x 1010 dis/sec

Also,

In terms of milli and micro, it can be represented as:

1 milli curie (mCi) = 3.7 x 107 dis/sec

1 micro curie (µCi) = 3.7 x 104 dis/sec

unit of radioactivity

c) Rutherford

1 Rutherford is defined as 106 disintegration per second. It is represented by symbol ‘Rd’.

1 Rd = 106 dis/sec

Also,

1 milli Rutherford (mRd) = 103 dis/sec

1 micro Rutherford (µRd) = 1 dis/sec

Read also: Half life and mean life

Relation between units of Radioactivity

Some mathematical relation can be drawn among different units of radioactivity.

1 Curie is equal to 3.7 x 1010 Bq

1 Rutherford is equal to 106 Bq

1 Curie is equal to 3.7 x 104 Rutherford (Rd)

FAQs

1) What is the S.I unit of radioactivity?

Ans: The S.I unit of radioactivity is Becquerel. It is represented by symbol ‘Bq’. One becquerel is equal to 1 disintegration per second.

 

2) 1 curie is equal to how many disintegrations per second?

Ans: 1 curie is equal to 3.7 x 1010 disintegration per second. That is, 37 billion disintegration per second.

 

3) 1 curie is equal to how many becquerel?

Ans: 1 curie is equal to 3.7 x 1010 disintegration per second. 1 becquerel I equal to 1 disintegration per second. So, 1 curie is equal to 3.7 x 1010 becquerel.

 

4) What is the CGS unit of radioactivity?

Ans: Curie is the CGS unit of radioactivity. In 1975, it was replaced by becquerel as S.I unit.

References

https://radiopaedia.org/articles/curie-unit

https://www.nrc.gov/reading-rm/basic-ref/glossary/curie-ci.html

https://www.nrc.gov/reading-rm/basic-ref/glossary/becquerel-bq.html

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