Monthly Archives: January 2012

The cost of coins

Posted on 23rd January by Mr Reid

It used to be the case that coins used as currency had value because of the material from which they were made: a solid gold coin weighing one ounce had the same value as one ounce of gold. The intro­duc­tion of … Continue reading →

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Technetium-99m generators

Posted on 15th January by Mr Reid

Technetium-99m is a radio­active tracer that is used in twenty million medical dia­gnostic pro­ced­ures per year. At least 31 radio­phar­ma­ceut­icals based on Tc-99m are used for imaging and studying organs such as the brain, heart muscle, thyroid, lungs, liver, gall­bladder … Continue reading →

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Plug wiring colour scheme

Posted on 6th January by Mr Reid

UK plugs use brown insu­la­tion for the live wire, blue insu­la­tion for the neutral wire and green with yellow stripes insu­la­tion for the earth wire. But why this par­tic­ular com­bin­a­tion of colours? The answer is decept­ively simple: there is no type … Continue reading →

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Night vision

Posted on 2nd January by Mr Reid

The vision of human beings is well-adapted to daylight; the human eye has evolved to see in the range of wavelengths that are brightest in the spectrum of light that the Sun emits. The intensity of the light the Sun emits … Continue reading →

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