Set up Cornell Notes on pg. 47

Topic: How to Use a Microscope

Essential Question:What can happen if you break the GOLDEN RULE of microscopes?

How to Use a Microscope

What can happen if you break the GOLDEN RULE of microscopes?

Introduction to the Microscope

• Always carry with 2 hands

• Only use lens paper for cleaning

• Do not force knobs

• Always store covered

• Keep objects clear of desk and cords

Eyepiece

Body Tube

Revolving Nosepiece

Body/ArmObjective Lens

StageStage Clips

Coarse Focus

Fine Focus

Base

Diaphragm/Light Adjust

Light

Eyepiece

Body Tube

Revolving Nosepiece

Body/Arm

Objective Lenses

StageStage Clips

Coarse Focus

Fine Focus

Base

Diaphragm/Light Adjust

Light

Objective Lenses

Inclination joint

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Guidelines for Using the Light Microscope

Microscopes are expensive instruments. They must be handled with care in order to avoid damage.

Keep the instrument in a box or under a cover when not in use.

Use only the supporting arm of the microscope to lift it.

• 1. Always start with the low powered objective lens (short)

• 2. Place slide on stage- clip in

• 3. Turn coarse focus knob all the way down (big knob)

• 4. Focus until clear using both focus knobs

• 5. Change magnification if necess.

• THE GOLDEN RULE

• 6. When using High power, NEVER EVER touch the coarse (big) focus knob

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Total Magnification

If a ×10 objective lens is used, assuming the eye piece magnification is ×10, the total magnification of the image will be (×10) × (×10) = ×100.

Eyepiece x Objective= TOTAL Magnification

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Select the Lowest Power Objective Lens

Use the short lens first!!!!!

It is normal practice to look at a specimen at the lowest available resolution first, then to look more closely at the specimen under a higher resolution.

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Placing the Slide on the Stage

Place the slide on the stage, so that the specimen is over the middle of the hole on the stage.

Make sure that light is shining through it and then secure it in place with the clips.

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Lowering the Objective Lens

Look at the stage and the slide from the side. Then lower the objective lens using the coarse focus dial. Lower the lens until it is about 5 mm above the slide. This is to ensure that the slide is not crushed and damaged by the objective lens.

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Getting the Specimen into Focus

Looking through the microscope eye piece, use the coarse focus dial to move the objective lens slowly upwards (never downward, as you could easily crush and break the slide). Do this until the specimen comes into focus. Try to keep both eyes open.

This will help to prevent eye strain and headaches.

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Adjusting the Diaphragm

The diaphragm can be adjusted to let different amounts of light through the specimen. This is because specimens vary in thickness.

Finding the amount of light that produces the best viewing results for each specimen is often a matter of trial and error.

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Minor Focusing Adjustments

The fine focus dial alters the height of the stage more accurately than the coarse focus dial.

You may need to make minor adjustments to the objective lens using the fine focus dial to get your specimen into sharp focus.

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Biological Drawings

There are two main reasons why it is useful to make drawings of biological specimens:

• As a way of studying the specimen in more detail

• As a record of what you have seen

• Follow steps to focus using low power

• Click the nosepiece to the longest objective

• Do NOT use the Coarse Focusing Knob

• Use the Fine Focus Knob to bring the slide

What can you find on your slide?

• 1. Raise coarse focus knob all the way up

• 2. Center the low power objective (short lens)

• 3. Remove slide

• 4. Lower coarse focus all the way down

• 5. Unplug cord

• 6. Wrap cord

• 7. Put cover back on

What are you looking at?What are you looking at?• Sordaria= fungus

• Volvox= green algae

• Rbizopus w.m.= bread mold

• Human sperm smear= sperm

• Zea Mays Stem = corn stem

• Allium Root Tip = onion root tip

• Epithelia= simple cuboidal kidney tubules

• Spirogyra Vegatative = Green algae

• Tilia Stem = type of tree stem

• Plasmodium Falciparum= Protozoan Parasite that causes Malaria in humans

• Diatom= algae

• Lilium leaf= Lilly leaf

• Fasciola Hepatica- Parasitic flatworm that infects the liver and causes “liver rot”