Question

The thickness of a micron is:
(A) $ 10^{-3}m $
(B) $ 10^{-6}m $
(C) $ 10^{-9}m $
(D) $ 10^{-12}m $

Answer 1

Hint :Micron is one of the measures for length that is used to measure the length, diameter or thickness of highly diminished or small sized objects like microorganisms, colloidal particles. Hence, naturally micron, also known as micrometer is a smaller unit than the standard unit i.e. meter and its thickness is related with the size of the microorganisms.

Complete Step By Step Answer:
We have defined a standard unit of measure in SI terms to measure lengths or linear dimensions which is known as meter.
Hence, the size of daily use items like machines, household items etc. and distances between objects, that is to say the dimensions that can be seen by the naked eye, can be written in terms of meters.
However, if we need to measure the size of smaller objects like micro constituents, microorganisms, atoms, nucleus, thickness of wire, thickness of a single hair, etc. which cannot be seen by naked eye, we need cannot use a meter scale to define them, whereas we need a scale of smaller unit.
Hence, certain smaller objects are defined to express the dimensions of the smaller objects. These smaller units are calculated by dividing the meter value with a specific power of ten.
The micron, or the micrometer is defined as the one millionth part of a meter. That means when one meter is divided by one million, we get one micron or one micrometer. The symbol to express micron is $ \mu $ .
Hence, the above statement can be expressed mathematically as
 $ 1\mu m=\dfrac{1m}{{{10}^{6}}} $
 $ \therefore 1\mu m={{10}^{-6}}m $
Hence, the correct answer is Option $ (B) $ .

Note :
The negative power $ 10^{-3} $ is known as millimeter and is used to measure objects in similar size to seeds. The negative power $ 10^{-9} $ is known as nanometer and is used to measure DNA strands, size of atoms, thickness of sheet of paper, etc. The negative power $ 10^{-12} $ is known as a picometer and is used to measure objects smaller than atoms like distances between atomic nuclei and electrons etc.