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Units and contamination

Dear Reader,

The IAEA have reported at distances between 35 and 68 km from the stricken plant that the level of contamination by beta / gamma emitters are at levels between 80 and 900 kBq per square meter.

At this point I would like to point out that until we know which isotopes have landed on the land that nobody can make a good assessment of the threat posed to the general public.

But we need to stop for a moment and consider what the symbols T, G, M k, m, n and p mean.

If you have a T before a unit then it means that the unit is 1000,000,000,000 times larger than the ordinary unit which does not have a prefix.

If you have a G before a unit then it means that the unit is 1000,000,000 times larger than the ordinary unit which does not have a prefix. For example the 3 cm microwaves used for both satellite TV and police radar speed guns have a frequency of 10 GHz.

If you have a M before a unit then it means that the unit is 1000,000 times larger than the ordinary unit which does not have a prefix. For example medium wave AM radio broadcasts are at about 1 MHz, for example virgin 1215 was always at 1.215 MHz.

If you have a k before a unit then it means that the unit is 1000 times larger than the ordinary unit which does not have a prefix. For example virgin 1215 in the 1990s was first at 1215 KHz, now the smarter ones of you reading will understand how 1.215 MHz and 1215 KHz are the same value.

If you have a m before a unit then it means that the unit is 1000 times smaller than the ordinary unit which does not have a prefix. For example the millimeter is 1000 times smaller than a meter. The width of a finger is about 10 to 15 millimeters

If you have a funny looking u (micro symbol) before a unit then it means that the unit is 1000,000 times smaller than the ordinary unit which does not have a prefix.

If you have a n (nano) before a unit then it means that the unit is 1000,000,000 times smaller than the ordinary unit which does not have a prefix. A medium sized molecule such as benzene is typically in the nanometer size range.

If you have a p (pico) before a unit then it means that the unit is 1000,000,000,000 times smaller than the ordinary unit which does not have a prefix.

I am sure that you can make up or find some more examples to use the different prefixes.

A final word of warning about the Bq and the curie. For many purposes the Bq is very small it is like trying to express the weight of a man in terms of grains of rice while expressing many everyday levels of radioactivity in curies is like expressing the weight of a cat in tons.

One curie is the same amount of radioactivity as is in one gram of radium-226 (Nightmare isotope), which is the old fashioned unit for radioactivity levels. While people in Europe tend to use Bq the americans still use curies. 

The Bq (becquerel) is one radioactive decay event per second which is a lot smaller.

One curie (Ci) is 37 GBq, now I imagine you can see why I think that the curie is too big for many uses while the Bq is a bit on the small side for many purposes. The way to deal with this problem is to use the prefixes.

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