Defining the Primary Measurement Units
First: Physical Calibration Department
It is defined by using the helium-neon laser interferometer with an estimated accuracy of (2.5 ×10-11 of laser wavelengths) according to the international definition. Metre "m" (unit for measuring length)
It is defined by using 8 fixed points according to the international scale for temperature degrees (ITS 90) from mercury point at - 8344, 38o C to silver point at 78,961o C ( + 0001,0o C to 03,0o C ). Kelvin "K" (unit for measuring temperature)
Second: Mechanical Calibration Department
It is defined by using the front model of the national kilogram (stainless steel) calibrated by the International Bureau for Weights and Measures with an estimated uncertainty of (+ 15 microgram). Kilogram "kg" (unit for measuring mass)
Third: Electrical Calibration Department
It is defined by using caesium atomic clock (2 × 10-12).
Coordinated Universal Time (CUT) is generated (at NMCC) by using the caesium atomic clock and comparing it to the time transmitted from GPS satellites (µs 3-2± (.
The second "s" (unit for measuring time).
It is defined as a basic unit by realizing two derived units volt and ohm by the equation: A = V / Ω
Ampere "A" (unit for measuring electric current)
It is defined through a group of electronic voltage reference cells on Zener Voltage Regulator, which is maintained at a high-constant temperature ±)µV/V 0.1).
The Volt "V" (unit for measuring Volt-measuring)
It is defined by using a group of standard resistors of 1 ohm maintained at a high-constant temperature with an estimated uncertainty of (0.06± microohms).
The Ohm "Ω" (unit for measuring electrical-resistance)