SI units and Quantities and Prefixes

Physical Quantities, SI Units

A physical quantity is a quantity which can be measured.
Examples of some of them are length, volume, mass, time, temperature, etc.

A non-physical quantity is one which cannot be measured.
Examples of some of them are beauty, kindness, humour, sadness, untidiness, etc.

Since 1960, scientists from different parts of the world have agreed to adopt a single system of units called the SI Units (SI stands for Système International d’Unités in French). This system is an adaptation of the metric system.

There are altogether seven basic quantities: length, mass, time, electric current, thermodynamic temperature, luminous intensity and amount of substance.

The International System of Units (SI units)

 The table below is the SI units

SI base units

Name	Unit symbol	Quantity	Typical Symbol for Variables
metre	m	length	l (a lowercase L)
kilogram	kg	mass	m
second	s	time	t
ampere	A	electric current	I (a capital i)
kelvin	K	thermodynamic temperature	T
candela	cd	luminous intensity	Iv (a capital i with lowercase non-italicized v subscript)
mole	mol	amount of substance	n

The SI unit is made to let foreign scientists at international events to understand the units as their native units are different from other countries'.

Prefixes:

Micro:

-Symbol: m, Value-10 to the power of negative 6, also 1 millionth, or 0.0000001

Milli:

-Symbol: m Value: 10 to the power of negative 3, also 1 thousandth, or 0.001

Centi:

-Symbol: c Value: 10 to the power of negative 2, also 1 hundredth, or 0.01

Deci:

-Symbol: d Value: 10 to the power of negative 1, also 1 tenth, or 0.1

Kilo:

-Symbol: k Value : 10 to the power of 3, also 1 thousand, or 1000

Mega

-Symbol: M Value: 10 to the power of 6, also 1 million, or 100000

This topic is quite easy, as I only need to memorize the prefixes and SI units. I thought of a technique to remember the symbol Milli and Mega, as their symbols are m & M and hence can be quite confusing. for Mega, I told myself capital m-ega, so when I combined them, it becomes Captaimega. When I knew one, i knew the other m was milli, so this method was effective for me.