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The '''curie''' (symbol '''Ci''') is a non-[[International System of Units|SI]] unit of [[Radioactive decay|radioactivity]], named after [[Marie Curie|Marie]] and [[Pierre Curie]].<ref>[http://www.britannica.com/eb/article-9028251/curie#245574.hook curie - Britannica Online Encyclopedia<!-- Bot generated title -->]</ref><ref>{{cite web
| author = Paul W. Frame
| title = How the Curie Came to Be
| url = http://www.orau.org/ptp/articlesstories/thecurie.htm
| accessdate = 2008-04-30}}</ref> It is defined as
: 1&nbsp;Ci = 3.7 × 10<sup>10</sup> [[radioactive decay|decays]] per [[second]].
While its continued use is discouraged by NIST<ref>Nist Special Publication 811, paragraph 5.2.</ref> and other bodies, the curie is widely used throughout the US government and industry.
 
One curie is roughly the activity of 1 [[gram]] of the [[radium]] [[isotope]] <sup>226</sup>Ra, a substance studied by the Curies.
 
The [[SI derived unit]] of radioactivity is the [[becquerel]] (Bq), which equates to one decay per second. Therefore:
: 1&nbsp;Ci = 3.7 × 10<sup>10</sup> Bq = 37 GBq
and
: 1&nbsp;Bq ≅ 2.703 × 10<sup>−11</sup>&nbsp;Ci
 
Another commonly used measure of radioactivity is the '''microcurie''':
: 1&nbsp;μCi = 3.7 × 10<sup>4</sup> disintegrations per second = 2.22 × 10<sup>6</sup> disintegrations per minute
 
A [[radiotherapy]] machine may have roughly 1000&nbsp;Ci of a radioisotope such as [[caesium-137]] or [[cobalt-60]]. This quantity of radioactivity can produce serious health effects with only a few minutes of close-range, unshielded exposure.
 
Ingesting even a millicurie is usually fatal (unless it is a very short-lived isotope). For example, the [[median lethal dose|LD-50]] for ingested [[polonium]]-210 is 240 μCi.
 
The typical human body contains roughly 0.1&nbsp;μCi (14&nbsp;mg) of naturally occurring [[potassium-40]]. A human body containing 16&nbsp;kg of carbon (see [[Composition of the human body]]) would also have about 24 nanograms or 0.1&nbsp;μCi of carbon-14. Together, these would have an activity of approximately 2×0.1 μCi&nbsp;or 7400 decays (mostly from beta decay and rarely from gamma decay) per second inside the person's body.
 
==Curies as a measure of quantity==
Curies are occasionally used to express a quantity of radioactive material rather than a decay rate, such as when one refers to 1&nbsp;Ci of [[caesium-137]]. This may be interpreted as the number of atoms that would produce 1&nbsp;Ci of radiation. The rules of [[radioactive decay]] may be used convert this to an actual number of atoms. They state that 1&nbsp;Ci of radioactive atoms would follow the expression:
: N (atoms) × λ (s<sup>−1</sup>) = 1 Ci =  3.7 × 10<sup>10</sup> (Bq)
and so,
: N = 3.7 × 10<sup>10</sup> / λ,
where λ is the [[exponential decay|decay constant]] in (s<sup>−1</sup>).
 
We can also express a Curie in moles:
:<math>\begin{align}\text{1 Ci}&=\frac{3.7\times 10^{10}}{(\ln 2)N_{\rm A}}\text{ moles}\times t_{1/2}\text{ in seconds}\\
&\approx 8.8639\times 10^{-14}\text{ moles}\times t_{1/2}\text{ in seconds}\\
&\approx 5.3183\times 10^{-12}\text{ moles}\times t_{1/2}\text{ in minutes}\\
&\approx 3.1910\times 10^{-10}\text{ moles}\times t_{1/2}\text{ in hours}\\
&\approx 7.6584\times 10^{-9}\text{ moles}\times t_{1/2}\text{ in days}\\
&\approx 2.7972\times 10^{-6}\text{ moles}\times t_{1/2}\text{ in years}
\end{align}</math>
where ''N''<sub>A</sub> is [[Avogadro's number]] and ''t''<sub>1/2</sub> is the half life. The number of moles may be converted to grams by multiplying by the [[atomic mass]].
 
Here are some examples:
{| class="wikitable"
|-
! Isotope!! Half life!! Mass of 1 Curie
|-
|<sup>238</sup>U ||{{val|4.471|e=9}} years|| 2.977 tonnes
|-
|<sup>40</sup>K ||{{val|1.25|e=9}} years||140&nbsp;kg
|-
|<sup>129</sup>I ||{{val|15.7|e=6}} years||5.66&nbsp;kg
|-
|<sup>99</sup>Tc ||{{val|211|e=3}} years||58 g
|-
|<sup>239</sup>Pu||{{val|24.11|e=3}} years||16 g
|-
|<sup>14</sup>C ||5730 years||0.22 g
|-
|<sup>226</sup>Ra || 1601 years || 1.01 g
|-
|<sup>137</sup>Cs || 30.17 years || 12&nbsp;mg
|-
|<sup>90</sup>Sr|| 28.8 years || 7.2&nbsp;mg
|-
|<sup>60</sup>Co||1925 days||883 μg
|-
|<sup>210</sup>Po||138 days||223 μg
|-
|<sup>131</sup>I||8.02 days||8 μg
|-
|<sup>123</sup>I||13 hours||0.5 μg
|}
The number of Curies present in a sample decreases with time because of decay.
 
==See also==
*[[Geiger counter]]
*[[Ionizing radiation]]
*[[Radiation exposure]]
*[[Radiation poisoning]]
*[[United Nations Scientific Committee on the Effects of Atomic Radiation]]
 
==References==
{{reflist}}
 
<!--Categories-->
[[Category:Non-SI metric units]]
[[Category:Radioactivity]]
[[Category:Units of radioactivity]]

Latest revision as of 09:40, 26 August 2014

If a child is going to burst, you need to be worried. Like obese adults, obese children expose themselves to a great deal of health difficulties which threaten his existence plus well-being. Obesity greatly reduces their quality of existence plus it is actually incumbent in parents to confirm which they are protected.

To calculate the waist-to-hip ratio (to keep an acronym it's called the WTHR), measure both your waist plus hips, plus divide the waist size by the hip size. And yes, this indicator realizes the difference between guys and women, unlike the BMI. For ladies, the ratio must be no more than 0.8. In different words, a waist must be smaller than your hips. And for men, it ought to be 1.0 or less. That signifies a man's waist should be the same measuring as his hips or small. The beer-and-pizza belly has to go!

Some persons think which it is wise to test and lose a limited pounds before computing for their body mass index. You should remember which carrying this out type of thing is similar to cheating throughout an exam at school. We need to measure a real weight inside purchase to receive a well-defined pic of how harmful we actually are. If you try to get rid of fat before the computation, we might receive a lower body mass index which may effectively mask the real condition. This can create we think which you don't have to go to the doctor or which you don't have to lose fat at all.

A great deal of people have benefited from the bmi calculator men over the previous few decades yet, there are more exact alternatives available nowadays. If you are not certain what system is ideal for a current condition, then you need to consult a health expert for right guidance.

As an example, your Body Mass Index! For adults, a BMI of lower than 18 is underweight, whilst between that and 24 is a healthy BMI. Anything over which is considered overweight. That means, a girl that is 5'4" ought to be around 130-140lbs to have a BMI of 23 or 24! Find what's appropriate for we and how comfortable we feel in a fresh body.

Another limitation is that age is not considered when calculating BMI. So for seniors, whether or not the BMI indication is regular, the fact remains that many muscles have been lost because of age.

The simplest method to help to make calories the friend is to add up how countless neighbors you have. You never need too countless neighbors, nevertheless we do not wish too little neighbors either. We would like the perfect balance of close friends that works for you in addition to a lifestyle.

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