The Microscope

Question 1

What is a Microscope for?

Answer 1

Microscopes are used to magnify objects so that we can observe thems

Question 2

Who invented the Microscope?

Answer 2

The first microscope was invented by Hans and Zacharias Janssen in 1595 in Holland by putting 2 lenses together. Their microscope has a magnification of 20 times.

Question 3

Robert Hooke used a microscope for what?

Answer 3

Robert Hooke used microscopes with 3 lenses to look at structures and properties of cork in 1665.

Question 4

Antoni Van Leeuwenhoek did what to microscopes.

Answer 4

Antoni Van Leeuwenhoek perfected the microscope by producing smaller lenses allowing for higher magnification.

Question 5

Compound Light Microscope.

Answer 5

Magnification: 2000X
Image :2D
Function:Uses light to illuminate a small slice of a specimen.

Question 6

Transmission Electron Microscope(TEM)

Answer 6

Magnification: 10 000X-100 000X
Image:2-D
Function:Uses a beam of electrons to project a 2-D image of the object being viewed.

Question 7

Scanning Electron Microscope(SEM)

Answer 7

Magnification:300 000X
Image:3-D
Function:A beam of electrons is swept over an abject to create a 3-D realistic view of an object.

Question 8

Confocal Laser Scanning Microscope(CLSM)

Answer 8

Magnification:300 000X+
Image:A series of 2-D images stitched into a 3-D image.
Function:Allows you to view objects that are too thick to be viewed by the compound light microscope.

Question 9

Scanning Tunnelling Microscope(STM)

Answer 9

Magnification:300 000X+
Image:3-D computer image
Function:A metal probe is used to follow the contours of an object and produces a realistic 3-D computerized image

Question 10

How to handle the Microscope.

Answer 10

1. Use two hands to hold the arm and the base.
2. Avoid touching the glass surfaces with your fingers. When necessary clean the glass surfaces with lens tissue. (Never Paper towel)

Question 11

Focusing the Microscope.

Answer 11

1. Plug in the microscope and put the low-power lens in place.
2. Place the prepared slides on the stage.
3. Lower the low power lens using the coarse adjustment so that the lens is as close to the slide as possible.
4. Look through the eyepiece and adjust the diaphragm for the greatest amount of light.
5. Slowly turn the coarse adjustment so that the objective lens goes up. Continue until the image comes into focus.
6. Move the slide around so that the image is in the center of the field of view.
7. Rotate the lenses to the next highest power. You should only use the fine focus to clearly focus on the object. DO NOT LET THE LENS CONTACT THE SLIDE.
8. Repeat with the next lens power.

Question 12

Preparing Wet Mount Slides.

Answer 12

1. Obtain a clean slide and coverslip. Handle only the edges.
2. Place specimen on the center of the slide and cover with 1 drop of water.
3. Lower the coverslip onto the slide at a 45-degree angle. Go slowly so air is not trapped under the coverslip.
4. If you need stain to see a specimen, add one drop of stain to one side of the coverslip and hold a small piece of paper towel to the opposite edge of the coverslip. As the liquid soaks into the paper the stain will spread through the specimen.

Question 13

Cleaning up the Microscope

Answer 13

1. Rotate the lenses so that the low-power lens is above the stage.
2. Remove the slide from the stage.
3. Unplug the microscope.
4. Wipe away any debris.
5. Replace the dust cover.
6. Put the microscope back on the cart in its correct spot.

Question 14

Determining Magnification

Answer 14

1. Determine the magnification of the ocular lens. The ocular lens that we will be using will always be a power of 10X.
2. Determine the magnification of the objective lens.
3. Multiply the magnification of the ocular lens by the magnification of the objective lens.

Total Magnification=(power of the ocular lens)(power of the objective lens)
Biological drawings must have the magnification that was used in the lower corner.

Question 15

Calculating the Field of View

Answer 15

1. Record the FV of the low power lens, as determined by your measurements.
2. Record the magnification number of the low-power lens.
3. Record the magnification number of the medium power lens.
4. Calculate the FV of the medium power lens.
   FV medium power=
   (FV low power X magnification of low power) /Magnification of med power
5. Perform the same calculations for your high power lens

Question 16

Due to the fact that objects viewed under a microscope the sizes may be given in millimetres (mm) or micrometres (μm). This means that you will need to convert between the two units.

Answer 16

1mm=1000 micrometres

Question 17

Convert 2.65mm to micrometers

Answer 17

2.65 X 1000 micrometers=2650 micrometers

Question 18

Estimating actual size

Answer 18

1. Determine the FV for each objective lens of your microscope.
2. Use both micrometres and millimetres as your units of measurement.
3. Compare the size of the structure being examined with the diameter of the FV of the specific objective lens being used.
4. Estimate the number of times the structure appears to fit across the field diameter. (“fit” number)
5. Calculate the approximate size of the structure as follows.

Size of specimen=FV/fit number

Question 19

Scale

Answer 19

Scale is the calculation you will make of drawings that you will draw in the lab. For this calculation, the units of the drawing and the actual size need to be the same.

scale=diagram size of object/actual size.

Question 20

Making a biological drawing.

Answer 20

1. Use plain, white paper.
2. Use a pencil only.
3. Use half a page for each diagram.
4. Draw a cluster of a few cells.
5. Draw only what you see.
6. Draw the outline of the structure only.
7. Draw labels with a ruler, horizontal line and all labels should line up on the right side of the diagram.
8. At the bottom of the diagram:
   Figure 1:Title: Description of the drawing.
   (Include type of slide preparation, name of specimens, type of stain, and magnification)
9. On the lower left-hand corner of the diagram shows:
   scale :1.0cm=10mm