Good Science Victorian Curriculum Year 7

CHAPTER 1: SCIENCE SKILLS
Get to know your light
microscope
2 Figure 1.4 A light microscope
can usually magnify samples
by up to 400 times.
Eyepiece
The most common type of microscope
in the school science laboratory is
a light microscope. It allows you to
study samples by shining a bright
light through an extremely thin slice
of material. The image is magnified
by the microscope’s lenses, which you
look through.
The eyepiece of a light microscope
already magnifies samples by ten
times. The objective lens, which is found
lower down and usually rotates, then
magnifies samples by a further amount.
To identify the total magnification,
multiply the eyepiece magnification (10)
by the objective lens magnification.
Coarse focus
Fine focus
Arm
Rack stop
Stage clip
Base
Revolving hosepiece
Objective lens
Stage
Condenser
Illuminator
SETTING UP AND USING A LIGHT MICROSCOPE
1 Place your microscope on the bench or table,
making sure that it’s not too close to the edge
and that the arm is facing you.
2 Plug your microscope in and turn it on.
The illuminator (light) will come on.
3 Lower the stage as far as it can go, using the
coarse focus knob.
4 Consider each of the rotating objective lenses.
Often they are different colours and have the
magnification written on them.
5 Start with the lowest magnification – this
is usually 4× (four times). Your microscope
eyepiece already has a 10× magnification on
its own, so when coupled with the 4× eye piece,
what you are looking at will be 40 times the
actual size.
6 Carefully insert the microscope slide onto the top
of the stage and hold it firmly under the stage
clip. Position it so the object you need to see is in
the middle of the stage.
7 Look through the eyepiece and slowly bring the
stage upwards towards you, using the coarse
focus knob. This can take some time and
everything will look bright and fuzzy until you get
a glimpse of the slide as it comes into focus.
8 When the slide is roughly in focus, use the fine
focus to turn it into a clear image.
9 Increase the magnification by changing the
objective lens to 10×, 20× or 40×.
10 40× is usually the highest available
magnification and can be tricky to find and
focus on. It can also bring the lens extremely
close to the slide, enough to crack and break it –
monitor this carefully.
Figure 1.5 Microscope slides are usually made of
glass and are very fragile – treat them carefully.
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