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Question
Answer the following in detail.
State some common rules to write SI units correctly.
Solution
Guidelines for capitalization:
Guidelines | Examples | |
Unit Names
Unit Symbols
Prefix Names
Prefix Symbols |
If a unit is derived from the name of a person, its name is always written in small letters. A unit not named after persons is written in small letters. The symbol used for a unit is normally written in small letters. If the symbol of the unit is derived from the name of a person, it is written in capital letters. If a unit is represented by more than one letter, the first letter of the symbol is capitalized.
Prefix names are written in small letters unless they occur at the beginning of a sentence. No space or hyphen is used between the prefix and the unit name. So a prefix name and a unit name are taken together as a single word.
Prefix symbols are attached to unit symbols without any space between them. Prefix symbols up to the kilo level are written in small letters but the ones with larger values are written in capital letters. |
newton (not Newton), joule (not joule)
metre (not Metre) second(not second)
metre : m (not M), second :s (not S) newton : N (not n), amphere : A (not a) pascal :Pa, hertz :Hz
milligram (not Milligram or milli-gram of a milligram), centimeter (not Centimetre or centimeter or) (centimeter) mg (milligram) M W (megawatt) |
GuidelinPrefix Symbolses for Plurals
Guidelines | Examples |
The plural form is used only when the unit is written in full. Symbols of units are never written in the plural. So, 's' is not added to the symbol of a unit. | 10 metres : 10 m(not 10 ms) 10 seconds : 10 s(not 10 ss) |
Guidelines for punctuation
Guidelines | Examples |
A full stop is never put at the end of a unit symbol unless it occurs at the end of a sentence. | "It is 50 cm long." but not "It is 50 cm. long." |
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