Microscopes

Microscopes are instruments used to produce an enlarged image of an object.

When dealing with microscopes there are 2 veryWhen dealing with microscopes there are 2 veryImportant terms!Important terms!

Magnification Resolution

An increase in an object’s apparent

size.

The amount of detail in the image.Which is more important??

Why???

Compound Light Microscope

• In this class, we use a compound light microscope.

• It uses light and two lenses (compound) to produce an enlarged image.

• Light must pass THROUGH the specimen, so your specimen must be thin!

This is the microscope you’ll usein this classroom.

Draw it!!(yes really)

OCULAR LENS – Has a magnification of 10x.

This is the lens you look through.

BODY TUBE – Connects ocular

lens to the objective lenses.

You raise this up and down to

focus.

BASE – Provides stability and support to the microscope.

ARM – Connects the body tube to the base of the microscope.

COARSE ADJUSTMENT KNOB – Moves the body tube up and down a

lot.FINE ADJUSTMENT KNOB –

Moves the body tube up and down a little.

PIVOT JOINT – Enables microscope to tilt. Don’t do it!

Your slide might fall.

NOSEPIECE – Holds the objective lenses.

STAGE – Place where you set your specimen. Has a hole

through which the light passes. Why do we need light again??

Again, here is the stage … you can see the hole for the light!

STAGE CLIPS – These hold the slide in place. Handy if you’re

not good at delicate movements!

Here is the nosepiece again. It rotates!

Above you can see the 3 objective lenses. These enable you to increase/decrease the magnification of

the object.

A good rule of thumb: the largerthe objective lens….

the higher the magnification!

SCANNING POWER – Has a magnification of 4x. You use this first to get an overview of

the slide you’re viewing.

LOW POWER – Has a magnification of 10x. This is the second lens you will use

when looking at a slide.

HIGH POWER – Has a magnification of 40x.

This is the last lens you will use. It is the most

difficult!

LIGHT SOURCE – Provides the light! Back in the day, this

used to be a mirror!!!

DIAPHRAGM – Controls the amount of light passing through

the stage.

Here you can see the diaphragm again.Notice the different sized holes.

You will want to play around to find thebest amount of light for each slide!

The higher the magnificationthe more light you will need!

Calculating Total Magnification

• Because these are COMPOUND microscopes and use 2 lenses, we need to multiply the magnification of the 2 lenses together.

• You will always be using the ocular lens which has a magnification of 10x.

• You will multiply the magnification of the objective lens you are using by 10x (the magnification of the ocular lens.

Let’s Try It!!!!

If you are viewing an object in scanningpower… What is the total magnification

of that object?

Scanning power is 4x.Ocular lens is 10x.So… 4 x 10 = 40x

If you are viewing an object in lowpower… What is the total magnification

of that object?

Low power is 10x.Ocular lens is 10x.

So… 10 x 10 = 100x

Calculate the magnification ofhigh power!!!!

How to Use the Microscope

• Start with the body tube all the way down.

• Set the slide on the stage so that the part of the slide you want to view is over the hole.

• Make sure you are on scanning power.

• Look through the ocular and slowly raise the body tube using the coarse adjustment.

Using the Microscope cont…

• When you have the image in focus, observe, draw, move the slide around etc.

• When you are ready, rotate the nosepiece to move the low power lens into place.

• The image should need just a BIT of focusing. Use the coarse and fine adjustment to do so.

• When you have the image in focus, observe, draw, move the slide around etc.

Using the Microscope cont..

• When you are ready for high power, rotate the nosepiece so the high power objective is in place.

• Using FINE ADJUSTMENT ONLY, focus the image.

• When you have the image in focus, observe, draw, move the slide around etc.

• When finished, rotate the nosepiece to put the scanning power objective in place again.

MAJOR RULES

• ALWAYS: Carry the microscope with 2 hands. One on the arm and one on the base.

• NEVER: Use the coarse adjustment in high power. You might jam the objective into the slide and break it!

• DON’T: Move the adjustment knobs before you switch between powers, you don’t have to!

• NEVER: Clean the lenses! Let me do it for you! You cannot ever use water!

Drawing what you see under the microscope.

Your field of vision in a microscope iscircular so what you draw should be

inside of a circle!

Draw what you see.Draw objects where you see them!

Label your drawings!Name of object.Magnification

Half Moons

100x

Other Microscopes

• The compound light microscope is just one type of microscope used in science.

• Electron microscopes use a beam of electrons instead of light. They can magnify things up to 200,000x!!

• Electron microscopes are large and expensive, but you can get some really neat images!

Electron Microscope!

Bird Feather 1500x

Spider!

White Blood Cell

Butterfly Tongue!

Other Microscopes cont..

• You may also encounter a dissecting microscope.

• These are used to view specimens through which light cannot pass.

• They are basically a powerful magnifying glass!

Don’t wait!Ask

Questions!