Microscopes

How are Microscopes Used?

• Micro “tiny” – scope “to view”• How big is a…..• Can see substances or structures not

visible to the naked eye• Magnify very small objects (not just living

things!)• Identify and Compare species• Measure size and compare

Word Bank• Eyepiece• Course Adjustment Knob• Diaphragm• Stage• Arm Support• Stage Clips• Base• Light Support• Nosepiece• Fine Adjustment Knob• Objective Lenses

On your Microscope, Label the Parts of the Compound

Light Microscope

Microscope Terms• Definition: clarity; how clear the specimen appears• Magnification: amount of enlargement of an image• Orientation: way in which something appears to be directed• Depth of Field: refers to layers, 3-D effect that is viewable

by changing fine adjustment under high power

• Width of Field: distance across the diameter of your field of view, used to estimate the size of a specimen

• Micrometer: metric unit of measure– 1millimeter = 1,000 micrometers

• Objective: degree of magnificationLow =Med =High =

Steps to Storing a Microscope1.) Turn off light and allow to sit for 5 min to cool

down.2.) Turn the stage all the way down.3.) Return objective to low.4.) Remove slide. Rest the stage clips on the

stage.5.) Loosely wrap and secure the electrical cord.6.) Turn the ocular over the body tube.7.) Cover the microscope with the jacket.8.) Carry the microscope with two hands.9.) Place the microscope in the closet with the

ocular pointing out.

Steps to Focusing a Microscope(Know in Order!!)

1.) Turn light on and leave it on for as long as you are using the microscope.2.) Align the slide on the stage and secure with the stage clips.3.) Turn the ocular towards you by rotating the base, not the tube.4.) Using the coarse adjustment, bring your specimen into view, and center it in

your field.5.) Adjust the diaphragm for the “best” lighting, not necessarily the brightest

setting.6.) Using your fine adjustment, sharpen your image (give the image definition.)7.) Using the revolving nose piece, turn to your medium power objective.8.) Using the coarse adjustment, bring your best image into view, center it, and

turn the fine adjustment for definition.9.) Turn the high power objective into place using the nosepiece. Using only

the fine adjustment knob, fine tune your image.10.) You may also want to change the light for a better image at this point.

What type of Microscope do I need to see…..

• Chloroplast (organelle)• Cancer Cells• Water Flea• Virus• Muscle Tissue• Snowflakes

What type of Microscope do I need to see…..

• Chloroplast (organelle)– SEM

• Cancer Cells– Compound Light

• OR SEM(depends on purpose)

• Water Flea– Compound Light

• Virus– TEM(color artificial)

• Muscle Tissue– Compound Light

• Snowflakes– SEM

Measuring Using the Microscope

We cannot just measure a specimen using a ruler, so we need to indirectly measure or compare the size to something we already know!

Width of Field or Width of View

WFLP = Width of Field Low Power

WFHP = Width of Field High Power

REMEMBER= Micrometer μm

Measure the WFLP

Place the ruler on the stage so that it covers half of the stage opening and you can see markings

GOOD

1. Make sure the ruler is centered at the center of the WF

2. What is the field of view in scanning power to the nearest in millimeters?

3. Switch to medium power and calculate the magnification.

4. You cannot measure the field for high-power, so you need to estimate……

Mag LP = WFHPMag HP WFLP

TOTAL Mag Estimated WF (using ruler)

Calculated WF

Low

Medium

High

Before measuring a specimen, you need a table like this….

Let’s try it #1…Ocular power = 10xLow power objective = 20xHigh power objective = 50x

a. What is the highest magnification you could get using this microscope?

b. If the diameter of the low power field is 2 mm, what is the diameter of the high power field in μm?

c. If 10 cells can fit end to end in the low power field of view, how many of those cells would you see under high power?

Mag LP = WFHPMag HP WFLP

Let’s try it #2…Ocular power = 10xLow power objective = 10xHigh power objective = 40x

a. What is the approximate width of the field of view in micrometers?

b. What would be the width of the field of view under high power?

c. If 5 cells fit across the high power field of view, what is the appropriate size of each cell?

Let’s try it #3…Ocular power = 10xLow power objective = 20xHigh power objective = 40x

a. If viewed under low power, what is the approximate size of the cell in micrometers?

b. What would be the high power field of view? c. How many cells like the

one in the picture could fit in the high power field of view?

2000 μm

CELL

Drawing in the Lab NotebookDrawing # : Title Date:

Total mag: Sig:

Observations:

WF(under total mag)# of specimen in field

Each drawing should consume ½ a page in

your notebook!cell

Making a Wet Mount

• Carefully angle the cover-slip and slowly place on the specimen.

• Water should NOT ooze out of the cover-slip

• Do not drop the cover-slip on the specimen- avoid bubbles

Whiteboard Discussion

• For the lowercase “a” drawing, what observations were you expected to make?

• In completing the paramecium drawing, what did you find about comparing the actual size of the specimen when you moved from low to high power? Did the image change? Did the specimen’s numerical width change?

• After creating the starfish development picture, were you able to relate the egg’s size to that of a different specimen in a different power (i.e. the paramecium in high power)?

• When you observed the last slide, how did you decide what power to draw that specimen under?

What is on the test???

• Microscope parts and functions• How to properly store a scope• How to focus an image (steps in order) • How to draw a specimen• Which microscope should I use?• Microscopic Calculations• How to work and use the scope (what

objective to use, how to draw, basically the lab)

It is all about perspective!

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