Transcript MICROSCOPES - Hudson City School District
MICROSCOPES
Microscope Quiz Friday –Jan. 28 Label parts of microscope How to use (ex: use coarse knob to find object, adjust diaphragm for light) Total Magnification (eyepiece X objective) How to Measure (field diam.
number across) Convert mm to µm (4 mm = 4000 µm)
Compound Light Microscope Parts
Compound Light
Uses two lenses
–ocular –objective
To bend light
Resolving Power Being able to tell two objects apart Measure of “clarity”-how clear it is
Resolving Power smallest separation between two object points that a given lens (or mirror) can still show as two distinct entities, not one ..
.
Pollen Under 1000X LM Over 1000 X SEM
MAGNIFICATION
Increase in the apparent size of an object
MULTIPLY THE OCULAR LENS x THE OBJECTIVE – OCULAR 10x – OBJECTIVE 40 x – WHAT IS THE TOTAL MAGNIFICATION?
–400 x
How do they look different?
Leaf 4X Leaf 10 X
ADVANTAGES of CLM: CAN MAGNIFY UP TO
1000 x
CAN VIEW
LIVING
THINGS Resolving power 200 nm or 0.2 µm
Disadvantages of LM Objects must be thin or transparent so light can go through them The image is inverted
Pictures of LM microorganisms Can be stained
Dissecting Light Microscope
Image is NOT inverted
Usually 40 X is the limit
Dissecting Scope Viewing
Light-colored stage for dark specimens and dark-colored st
a
ge for light ones
Dissection Scope View of Insect Wing
ELECTRON MICROSCOPES USE
MAGNETS
TO FOCUS A BEAM OF
ELECTRONS
–
TEM
(Transmission Electron Microscope) –
SEM
(Scanning Electron Microscope)
TEM Advantage
Can magnify 1000 X’s more than a light microscope (Uh…1000 X 1000 =
1,000,000 X’s )
Resolving power 0.2 nm
TEM Disadvantages
Must be in a vacuum (dead) Sample must be VERY THIN (less than 0.2 nm)
TEM
Images
SEM
: Scanning Electron Microscope Advantages Electron beam scans the surface Resolution 10 nm Magnifies 1,000,000 X’s
SEM Disadvantages Must be in a vacuum (dead) Cannot see internal structures
SEM
Images house fly and its mouth
Choose Critter and Change Image Molecular Expressions Microscopy Primer: Electron Microscopy Interactive Java Tutorials - Virtual Scanning Electron Microscopy
SPM
-Scanning Probe Scanning Probe Microscope Viewed ATOMS!!!!!!!!!!!
Does
not
need sample in a vacuum Magnifies
10 million times
SPM
Images (50 um X 1.4 um) Steel Surface
SPM
Images DNA
FIRST TO VIEW ATOMS!!!
Light Microscope
SEM
H
TEM Cinda Sheldon
CHOICES: Diaphragm Objectives Ocular Coarse knob Fine knob Base Revolving nose piece Stage and stage clips Arm condenser Label the parts:
Ocular (eyepiece) Arm Coarse knob Fine knob (little) Label the parts: Revolving nose piece Objectives Stage and stage clips Diaphragm Condenser base
Always begin on lowest lens
That is, as you increase magnification, the actual field of view becomes proportionally smaller.
4OX 100X 400X
Use REVOLVING NOSEPIECE – don’t grab lenses
Eye Specimen
Depth of Field = to the thickness of the plane of focus
Viewing “F” with A Light Microscope Which is an “F” put in a compound light and a dissection light microscope?
Field of View What is the approximate width in mm?
In µm? (1 mm = 1000 µm) 4 mm 4000 µm
Why use the letter “e?”
Do the math: one millimeter (mm.) = 1,000 micrometers µm So 5.5 mm = ________ µm
5500 µm
NOTE!!!!!!!!!!!!!!!!
The field diameter at high power is
proportional
to the ratio of the low to high power objectives. If 40X is 4000 µm 400X is 400 µm
FD = field diameter Low power FD X low magnification high power magnification = high power FD
Use when object is between the mm markers
Why do you need to know Field Diameter?
You may wish to estimate the size of the specimens (e.g., cells) you will see in lab.
Field of View What is the approximate size of this cell?
In mm?
In um?
If 5 fit across…
O.4 mm 400 µm
If the field of view in this question is 2 mm… How long is one cell?
2 mm
If the field of view in this question is 2 mm…
If 3 cells fit across then, one cell is:
2 mm
2mm 3 =.67 mm
Wet Mount 1. Add drop of water 3. Add cover slip 2. Place Specimen on 4. Tap out bubbles slide
Making a Wet Mount Slide Add drop of water Add cover slip