Units of Length

The basic unit of length is the metre.
The main units of length that you will use or come across are:

kilometre (km)
103m

decimetre (dm)
10-1m
centimetre (cm)
10-2m
millimetre (mm)
10-3m
micrometre (µm)
10-6m
nanometre (nm)
10-9m
(Angstrom (Å)
10-10m)
picometre (pm)
10-12m )




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deci-

deci- is a new prefix in this activity and means a tenth.

Thus a decimetre is a tenth of a metre.

You therefore know that there are
10 decimetres in 1 metre.

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centi-

centi- is a new prefix in this activity and means a hundredth.

Thus a centimetre is a hundredth of a metre.

You therefore know that there are
100 centimetres in 1 metre.

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micrometre = micron.

The micrometre is also known as a micron and you will see micron used in some text books.

There are a million microns in 1 metre.

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The Angstrom

The Angstrom is not really part of this series of units but it is used for measurements and you therefore need to know it.

There are ten billion Angstroms in one metre.

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