A brief introduction to the microscope, including parts, how to use and how to care for a classroom microscope.

1. Microscopes
Year 8 Science

2. Seeing things differently
Microscopes expanded our horizons in more
ways than many of us realise.
What do you take for granted today, that
would not have been possible without the
microscope?

3. What is a microscope?
A microscope is an instrument that produces an enlarged image
of an object. Biologists use microscopes to study things that are
too small to be seen with the unaided eye

4. The light microscope
Most microscopes are called light microscopes because they
accomplish their task by using lenses to bend light rays.

5. Parts of a Microscope
Eyepiece (Ocular): Usually contains a 10X lens.
Arm: contains the housing for the fine and coarse adjustments and
connects the base of the microscope to the nosepiece and ocular.
Nosepiece: A rotating head that has the objective lenses attached to it.
The lens to be used should "click" into position when the wheel is
gently turned so that it is directly over the speciman slide.
Objective: Basically a housing for a lens. Our microscopes have three
objective lenses - 4X, 10X, and 40X.
Stage: The specimen slides rests on this part of the microscope.
Light source: Located directly under the stage.

6. Parts of a Microscope
Coarse adjustment knobs: The larger of two sets of knobs located on
either side of the arm, just above the base. This adjustment is used to
make large adjustments in focusing by moving the lenses up and
down. Never use this adjustment when using the 40X objective.
Fine adjustment knobs: The smaller of two sets of knobs located on
either side of the arm. This adjustment is used to make small
adjustments in focusing. It has a limited amount of movement and is
most efficiently used after focusing with the 4X objective and coarse
focus, then increasing magnification and making final adjustments with
the fine focus knob.
Adjustable diaphragm: This rotating wheel on the underside of the
stage allows the user to adjust the amount of light that passes through
the specimen. As a general rule, the lowest intensity of light that allows
you to resolve the structure of the object you are viewing should be
used.

7. Now its your turn!
Complete the provided sheet, labelling all the parts of the
microscope.
This sheet is also available in your eLocker.

8. Care and Handling
A microscope is a delicate piece of equipment and should be
treated with care.
Use two hands when carrying the microscope. Place one hand
around the arm of the microscope and the other under the base
for support.
Carry the microscope upright and close to the body.
Place the microscope flat on the table, but not too near the
edge where it might be knocked off.
DO NOT slide the microscope back and forth on the lab table.
If it becomes necessary to clean the lenses on the microscope,
ask your teacher for a piece of lens paper. Other materials, such
as paper towel, can scratch the surface of the lens.

9. Important!
Magnification: the increase of an object's apparent size.
Field of view: the area visible through the microscope lenses.
Field of view decreases as magnificaiton increases.
Resolution: the power to show details clearly. Resolution allows
the viewer to see two objects that are very close together as two
objects rather than as one.
Compound microscopes use multiple lenses to produce an
increase in magnification. If the eyepiece lens enlarges by a
factor of 10 (10X) and the objective lens enlarges by a factor of
40 (40X), the total magnification is the product of the two -
400X.
Resolution is controlled by the quality of the lenses being used -
the better the lenses, the better the resolution.

10. How to draw what you see.
• For drawings only, use pencil - you can erase and shade
areas.
• Begin by identifying the area viewed through the microscope
with a circle.
• Specimens should be drawn to scale. If the specimen takes
up the whole viewing field, make sure your drawing shows
this.
• Drawings should be labeled with the specimen name and
magnification.
• Drawings should be large enough to view details and have
significant details labeled.
• All labels should be written on the outside of the circle.

11. Your turn again!
Set up the microscopes.
Use the pre-prepared slides to practice focusing.
Pay close attention to resolution, magnification and the field of
view.
Draw three examples of what you see in your exercise books.