A nanogram (ng) is a metric unit of mass in the International System of Units (SI). It represents one billionth of a gram or 10^-9 grams. The metric system is a decimal-based system of measurement used worldwide, and it provides a convenient way to express very small quantities of mass.
To put the size of a nanogram into perspective:
Nanograms are commonly used in various scientific and analytical fields where precise measurements of tiny quantities of substances or particles are necessary. Some examples of their usage include:
The kilogram (kg) is the base unit of mass in the International System of Units (SI). It is defined as the mass of the International Prototype of the Kilogram (IPK), a platinum-iridium cylinder kept at the International Bureau of Weights and Measures (BIPM) in France.
Until May 20, 2019, the kilogram was defined by the physical prototype, but as part of the redefinition of the SI units, the kilogram was redefined in terms of fundamental constants. Since that date, the kilogram is defined by fixing the numerical value of the Planck constant (h) to be exactly 6.62607015 x 10^-34 joule-seconds.
This redefinition ensures that the value of the kilogram is now based on a constant of nature rather than relying on a physical object that could potentially change over time. It allows for a more precise and stable definition of the kilogram and other SI units.