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Why does
glass work better than water at magnifying things?
Glass
has a larger refractive
index than water, so light travelling through a sphere of glass
is bent much more than when light travels through a sphere of water
of the same size. So it can magnify it better.
Why use a
sphere?
A sphere has a highly curved surface, which makes for a very powerful
lens. The diameter of the sphere determines the magnification —
the smaller the diameter, the greater the magnification.
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Leeuwenhoek's microscope: move your mouse over the different parts for more information |
Who
invented the microscope?
Strong
lenses have been used since antiquity to examine tiny objects. One of
the earliest uses of a simple microscope was by Antony van Leeuwenhoek
(1632-1723) in around 1680. Leeuwenhoek was a Dutch fabric merchant
who used little "glass pearls" to examine the textiles in detail.
Leeuwenhoek began to observe everything around him from saliva to
pond water to beer. He discovered many micro-organisms and was the
first person to describe bacteria,
blood cells and sperm cells. To obtain ever-increasing magnifications,
Leeuwenhoek worked on smaller and smaller lenses, finally reaching
1-2 mm (0.04-0.08 in.) diameter lenses. Such small and powerful lenses are difficult
to handle and focus: you have to keep the instrument very close
to your eye and look directly through the tiny lens.
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