Jedinica mjeseca: KELVIN Imajući u vidu da je na sjevernoj hemisferi zima i da spoljašnja temperatura već uveliko opada, ovog mjeseca fokusiraćemo se na kelvin, osnovnu jedinicu SI za termodinamičku temperaturu. Tačno mjerenje temperature od ključnog je značaja u brojnim svakodnevnim procesima, od kontrolisanja hemijskih reakcija i proizvodnje hrane do procjene vremenskih prilika i klimatskih promjena. Osim toga, skoro svaki inžinjerski proces zavisi od temperature – ponekad drastično. Tačan podatak o temperaturi je takođe veoma važan, ali često i nedostupan, pogotovo u ekstremnim uslovima, kao što su intenzivno visoke temperature neophodne za proizvodnju čelika ili veoma niske [...]
Unit of the month: AMPERE Electric current, for most of us, seems to appear mysteriously from electrical sockets and gives life to our appliances. Just like the blood in our veins, an electric current is flowing through the “conductive arteries” in our homes, powering the everyday equipment we need. That’s why we consider our unit for the month of January to be a bit of a hero. In 2019, the ampere – the SI base unit of electric current – will be undergoing some changes. Today, electricity is so common that most of us rarely give it [...]
Unit of the Month: Candela Fairy lights used for decorating are a good way of visualising the candela, the SI unit of luminous intensity. The light from a single clear indoor fairy light is approximately one candela. Both traditional filament fairy lamps and modern LED versions have similar luminous intensity, despite the fact that LEDs consume a tenth of the electricity. The candela is the only SI base unit linked to human perception. However, the eye cannot see all light colours equally well. The eye is most sensitive to yellow-green light, approximating the peak frequency of solar radiation [...]
Unit of the month: METRE A metre is the distance travelled by light in 1/299792458 of a second. The reason we use the distance travelled by light in a certain amount of time is because light is the fastest thing in the universe (that we know of) and it always travels at exactly the same speed in a vacuum. This means that if you measure how far light has travelled in a vacuum in 1/299792458 of a second in France, Canada, Brazil or India, you will always get exactly the same answer no matter where you are! On 20 May [...]
On the 20th of each month we will be exploring one of the SI base units. If you click on the next field you can learn about the way these units are used in everyday life, how they are currently defined and which changes to definitions will be introduced on 20 May 2019.