Lab 1- Introduction to Microscopy Flashcards
- Why do we use oil?
o To prevent the bending of light rays (refraction)
o 4x
scanning lens
o 10x
power lens; useful to view most eukaryotic cells
o 40x
high dry lens, used to view most eukaryotic cells
o 100x
oil immersion lens, used to bacterial specimens
- Ocular lens
eyepiece, magnifies imagine (10x)
- Diopter ring
focusing ring located near the bottom of left ocular, for eyesight adjustment
- Objective lens
magnify the imagine (4,10,40,100x)
- Stage
platform to support slide
- Mechanical stage
allows movement of the slide
- Slide holder
secures slide on stage
- X-axis knob
moves slide right and left across stage
- Y-axis knob-
moves slide forward and background across stage
- Coarse focus knob
rapidly brings specimen to focus
- Fine focus knob
- slowly brings into sharp focus
- Condenser
focuses light on specimen and fills the lens with light
- Iris diaphragm
controls amount of light leaving the condenser
- Condenser focus knob-
raises and lowers the condenser
- Base
support microscope
what are the Objective Lens for Viewing Eukaryotic Specimens
Eukaryotic cells are typically larger (10-100 µm), so they can be observed using:
* 10x or 40x objective lens for general viewing.
* 100x objective lens (with oil immersion) if finer details need to be observed.
what are the Objective Lens for Viewing Prokaryotic (Bacterial) Specimens
Prokaryotic cells (bacteria) are much smaller (0.2-10 µm), requiring higher magnification:
* 100x objective lens with oil immersion is typically used for bacteria to achieve sufficient detail.
Define and Calculate Magnification
- Magnification refers to how much larger an object appears compared to its actual size.
- Total Magnification = Ocular Lens Magnification × Objective Lens Magnification
o Example: If the ocular lens is 10x and the objective lens is 40x, the total magnification is:
10x × 40x = 400x
Define Resolution
- Resolution is the ability to distinguish two closely spaced objects as separate.
- Higher resolution allows for clearer and more detailed images.
When and Why is Immersion Oil Used in Microscopy?
- When? Used only with the 100x objective lens.
- Why? Immersion oil has a refractive index similar to glass, which prevents light from scattering and improves resolution at high magnification.
Proper Use of a micropscope
o Always start with the lowest objective lens (4x or 10x) and increase magnification as needed.
o Use coarse focus first, then fine focus for clarity.
o Adjust diaphragm/light intensity for optimal brightness.
Proper cleaninf of the microscope
o Use only lens paper to clean lenses (no rough cloth or tissues).
o Remove immersion oil from the 100x lens immediately after use.
