Tuesday, 16 June 2020

Conventions in writing SI Units



The following convensions (rules) should be strictly followed while writing SI units.
i.    While writing a unit, only its singular form is used.
For example, the mass of any substance should be written as kg not as kgs.
Distances should be expressed in km not in kms,
e.g., ten kilogram is written as
  10 kg                          10 kgs
(correct)                      (incorrect)

ii.  The abbreviation of any unit does not have full stop (.) at the end, unless it appears at the end of a sentence. Therefore, no full stop is placed either in between or at the end of the symbol of the unit.
For example,
      kg                   kg.                                      cm                              cm.
(correct)          (incorrect)                              (correct)                      (incorrect)

iii. One space is left between the last digit of a numeral and the symbol of the unit.
For example,
10 m                      10m                                                   5 g                              5g
(correct)                (incorrect)                                    (correct                   (incorrect)

iv.  Words and Symbols should not be mixed.
For example,
Kilogram per cubic metre    kg/m3             kilogram/m3              kg per cubic metre
(correct)                            (correct)          (incorrect)                  (incorrect)

v.  With numerals, the symbol of the unit should be written.
For example,
100 cm                       one hundred cm                   100 centimetres
(correct)                      (incorrect)                              (incorrect)

vi.  The names of the units derived from people’s names are written in small letters.
For example, the unit named after Joule is written as joule, (symbol: J).
The unit of force named after newton is written as newton, (symbol: N).

 vii.  The sign of degree (°) is not written when Kelvin scale is employed.
For example, temperature of 273 kelvin is written as 273 K and not 273°K.
  273 K                          273°K
(correct)                      (incorrect)

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